Empire of the Sun Rules & Tactics Intro: Air Naval Combat

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A few months ago, I pointed our customers to The Player’s Aid website as a site that creates consistently high-quality articles about our games (and others). I asked Grant, one of their founders and content creators, if he’d like to write an occasional article for InsideGMT to provide some added content to our site, and also to help spread the word about their site to an even broader group of readers. He wrote us a nice article about playing the Americans in Combat Commander which is now part of a larger series on their site.  Today, the guys from The Player’s Aid  are back with a new article, this time from Alexander, another of their founders and key writers. He takes us inside air-naval combat tactics in Mark Herman’s Empire of the Sun. I hope you all enjoy the article and The Player’s Aid site! – Gene

Welcome to the latest installment of Empire of the Sun Rules & Tactics Intro. Today we’re going to be taking on the first in a few articles about conducting different kinds of offensives. We’ll be breaking down combat into manageable, yet thorough chunks. Today we’ll look at Air Naval combat which, unsurprisingly, involves ships and airplanes. In later articles we’ll cover ground combat, combined offensives, and amphibious assaults, each with different nuances and layers. For a more general overview of the game you can read an introduction here.

This is a continuing series, so for brand new readers/players there’s going to be some assumed knowledge in this article. I’m not expecting you to have memorized the rule book, but anything that was covered in the previous two posts is going down in the ‘presumed knowledge’ category. If you haven’t read those they cover ZOIs and Strategy Cards.

Eligible Units

It might seem patronizing, but we’re going to first start with which units can participate in Air Naval combat, and before you yell at me ‘air and naval units’ we’re just going to cover a few bits and pieces to clarify how these things work. On the left of Figure 1 we have a late game Long Range Bomber [LRB] which` are primarily used for Strategic Warfare which affects hand draw size (more about that here). Another use for them is as part of getting the Japanese empire to surrender under the threat of an A-Bomb in range of the home Islands. Sometimes you’ll get caught up in all these ancillary abilities and uses, but don’t forget, they’re also very powerful bombers that can participate normally in air/naval combat. Their real power lies in that range, making them extremely flexible with regards to moving all over the board to support combats in seemingly remote areas.

Figure 1: A selection of Air/Naval units for illustrative purposes

Most non LRB air units have numbers above their range value which is their extended range. In Figure 1 the allied 1MAW have their extended range in parentheses, whereas the Japanese 1st Air does not. A unit with parenthetical extended range may not participate in air/naval combat if at any point it used that extended range to move. All other air units may use their extended range and still fight, however they will fight at half strength. From a strategic standpoint, you can see the advantage that the elite Japanese pilots will have early on with their extremely high attack values, and even when halved they’re still as strong as any allied unit out there. As far as Naval units are concerned mostly they have to move into the battle hex to participate in combat, but carriers of all forms are an exception to that rule.

All air units may not move into the battle hex, and carriers do not have to move into the hex to launch their fighters and attack. That being said, air units in a hex declared as a battle hex must participate and is one of the only times air units are allowed in a battle hex. Basically you want to position your carriers and air units away from the fray but within range so they “sortie” into the battle hex within range, they’re still eligible for hits, but air units cannot be used to capture a hex if they’re the only ones remaining.

Getting Started

Let’s dive right into Air Naval combat. Mark Herman wanted to model the importance of air and naval superiority in the Pacific Theater of Operations of World War II and having separate air naval rules/DRMs helps to highlight that. Most of this post will be an extended example of combat, but we’ll be covering most, if not all, of the ‘other’ situational rules that could occur. Air Naval combat will be utilized early and often in the game as the two sides vie for positioning in shipping lanes and strategic one-hex-islands deep in the Pacific Ocean. So here’s a look at some early war units duking it out in combat.

Figure 2: A small allied force occupies the Admiralty Islands (3820) supported by the South Pacific HQ (4423)

We’ll look at a completely hypothetical situation in order to try and use as many different rules and examples as possible, so Figure 2 shows the set up for this little example. The Allied forces occupying the Admiralty Islands look to be outmatched, but we’ll see if they can withstand the Japanese attack and live to fight another day. Figure 3 below is a close up of the Allied units; even at a cursory glance they are woefully under-prepared and poorly equipped in order to resist the Japanese expansion.

Figure 3: Allied Units include the Generic Destroyer ‘US Asia’, and the 1MAW which came onto the board during the second game turn [as denoted by the 2 in the top left hand corner of the counter].

The Allies currently have a combat value of 8, which is frankly very bad, so the Allies are going to be relying on hopefully being able to bring in reaction forces to the battle once the offensive begins proper. The Japanese player opens up the Offensives Round by checking to see if they are currently in ‘Inter Service Rivalry’. This is a very important check, because if you are in inter-service rivalry then that means you cannot coordinate army and navy units together in the same offensive. For the Japanese player that’s the white pieces (navy) and the yellow pieces (army), for the Allies that’s blue (navy) and green (army). This represents the different branches of the military being at loggerheads and unable to agree or to commit forces upon a single tactic/offensive. [Ed – as an aside the Allied Inter-service rivalry only affects the US forces. Commonwealth, Dutch, and Chinese forces are unaffected]. Usually this rivalry comes about as the result of the opponent playing an event card that instigates this condition. Trust me when I say this, check before EVERY offensive, because there’s nothing more sickening than performing a wildly successful offensive and making huge headway in the game, only to find out that it was an illegal move, because you couldn’t combine forces in the right way. Trying to backtrack in this game after all the post battle movement can be a real pain. SO JUST DOUBLE CHECK! That’s one of the biggest rookie mistakes; don’t fall into the trap!

Offensives Card

The Japanese player uses a military event card to conduct the offensive, for a more detailed look at the cards and everything printed on them, go ahead and read here first. Figure 4 shows the card being used this turn, which actually happens to be the Solomon Island Expansion. As an aside I feel like the events on the cards and the things that happen with them often don’t line up from a historic/geographic standpoint, but usually cards with a specific historic event will encourage and aid you doing something at least very similar from a strategic standpoint.

Figure 4: Offensive card played is the ‘2nd Operational Phase’ Military Event card.

The card has an Operations value of 3, and will be played for the Event, so the EC intelligence number is 7, so in theory it should be easy enough for the Allied player to roll under that number [with a 10 sided die] in order to react. The Japanese player first chooses an HQ to activate, in the example there’s only 1 available; the South Seas HQ (4017) but in a real game the Japanese player could activate any HQ as stated on the card itself. Also of note, are the conditions of the event, which dictates that the Japanese may not use the Event on the card if there is Inter-service Rivalry, so good thing we aren’t and we checked that earlier. The logistics value states that 6 units can be activated by the designated HQ. On top of that, a number of units can be activated equal to the efficiency rating of the HQ, the big red and white number in the bottom right of the HQ. So the Japanese can bring 8 units (6 from the Offensive card and 2 from the HQ) into battle with this single card. Overkill? We’ll see.

Unit Activation

Figure 5: The Japanese player activates a number of units within command range equal to the logistics value of the Offensives Card plus the efficiency rating of the HQ

South Seas HQ has a command range of 12, printed on the counter, which means it can activate units within that range. It’s not necessarily a radius because the path traced by command activation might have to curve around enemy ZOIs, for more on that you can read here. In this example in Figure 5 the activation path from South Seas to hex 3520, the 2nd Air corps, wouldn’t actually be a straight line as hexes 3818, 3819, and 3718 are un-neutralized ZOIs, but there’s still plenty of command range to circumvent those hexes and make it to activate the Army Air unit. It should also be pretty obvious why Truk (the island hex that South Seas HQ is located in) was so strategically important for the Japanese. Truk can activate units all the way back in the home islands and will do so as part of the offensive, so let’s take a look at which units are back in Japan that will join the fray.

There are two stacks totaling 5 naval units that can activate. Combined with the Hiei in hex 3615, and the 2 air units stationed in New Guinea that’s a total of 8 units being activated, the maximum possible allowed. As you can see, those combat values are pretty hefty and the Japanese player should be able to bring a lot of firepower to bear on the small allied forces.


Naval units have a base movement of 5 hexes. This number is multiplied by the Operations Value of the offensives card played, in this case 3. So each naval unit can move 15 hexes into the fray in this example. In Figure 6 the purple lines represent the movement of Carrier units, which will congregate in hex 3817 just north of the declared battle hex (3820). From this hex they can use their range of 3 to participate in the declared combat. The carriers’ aircraft are abstracted by that range value, and you just have to imagine that planes are launching from the decks and flying three hexes to fight. The red arrows show the movement of the non-carrier naval units that have to move into the declared battle hex in order to participate in the combat. So all in all the Mogami, Nachi and the Hiei all move into the battle hex, whilst the 3 carriers all wait on the fringes in order to contribute from afar.

Figure 6: Japanese Carriers move to hex 3817 to use their fighters’ range to attack, whilst all other naval units must move into the battle hex

Next, we’ll move the aircraft. There’s no strict order of when you move which units when, I just chose to do ships then aircraft to keep the diagrams as clear as possible. The Aircraft move in legs, the length of which is their movement value. The number of legs an aircraft can fly is determined by the operations value of the card being used, which once again are 3. This means that the 24th air unit in hex 3319 can fly 3 legs of 3 hexes each [pictured in Figure 7]. It does not need to use all of that movement as it can land in the already friendly airfield in hex 3520 where the 2nd Air force unit is already stationed.

Figure 7: Japanese 24th air unit move into attack range in order to contribute to the air-naval combat.

In Figure 8 (below) the air units share the same hex (3520). The 24th air unit can trace 3 hexes to the battle hex (3820), determined by its range; and in doing so can contribute its full combat value of the battle. The 2nd air unit on the other hand has a range of 2, and the battle hex is too far away to contribute its full combat strength. The extended range is 4, which it can use to reach the battle hex. Note the extended range is not in parentheses and therefore will contribute half the combat strength, still a reputable 10 strength. Like we discussed earlier, had the extended range been parenthetical then it could not have contributed any combat strength to the battle.

Figure 8: The air units stop their movement and ‘sortie’ into the combat from afar. The yellow 2nd air unit has to use extended range to fight in the battle hex, and in so doing can only use half its combat strength.

With the air units moved into position that concludes the movement phase for the Japanese player. It’s at this point of the turn that the Japanese player would officially declare hex 3820 as a battle hex, meaning they could have done other non-combat movements with their unit activations instead. But all movements have to be completed before any combat takes place. In this case, however, all of the activated units are being utilized in the battle hex.

Offensive Intelligence Condition Determination

That’s a lot of big words, but it basically means, how much did the attacker catch you by surprise? This was touched upon in the Strategy Cards article but basically the bigger your offensive is, and the more units you bring into the fight, the easier it is for the defender to spot you coming and have an opportunity to react. Reactions involve bringing in reinforcing units to bolster your defense and try to turn the tides of battle.

Figure 10: Final positioning of Japanese units after movement, Japanese Hiei stack are also in hex 3820, but are side by side for ease of reference.

The Japanese units have all finished moving and Figure 10 shows their layout, clearly they outnumber the Allies but let’s see what the Allies can scrape together for a defense. Offensive intelligence condition can be determined in 1 of two ways. Either with the play of a reaction card that will have a written determination of the intelligence level, or absent that there is the potential for a die roll in order to affect the intelligence level. Let’s take a look at the die roll option, if the reaction player has no reaction cards, or opts not to use one, then they may attempt a die roll to change the intelligence level from the default of ‘surprise attack’ to ‘intercept’. There’s a caveat here, where all offensives start by default as a ‘surprise attack’, and can be changed except when the Offensive Event is being used and it specifically dictates a surprise attack [it will say ‘Intelligence: Surprise Attack’ on it]. When the card text states surprise attack, a die roll may not be attempted. In most occasions, however, the die roll can be tried, the reaction player tries to roll equal to or under the intelligence number, OC, or EC as stated in the gold box in the top left hand corner of the card. In this example, the Japanese player used an Event [Figure 4], so the reaction player rolls against the EC intelligence number – which is 7. On a 10-sided die it’s going to be very easy to make this roll, especially because in Empire of the Sun, the 0 on the die is actually a zero, and not a ten, which is usually the case when utilizing a 10-sided die. Also of note is a single DRM of -2 if at any point during the movement phase the offensives player moved into, out of or through an enemy ZOI. This is what I meant by saying the bigger the offensive, the easier it is to spot. Most events that can bring a lot of units to bear will have a high target number on them. Good luck in trying to sneak a massive carrier fleet across the Pacific!

Figure 11: The Reaction player opts to play a reaction card in order to change the intelligence level, doing so bypasses the need for a die roll.

The other option is for the reaction player to play a reaction card that explicitly states in writing what the intelligence level is changed to, this supersedes any previous intelligence level. In this case (Figure 11 above) from the default surprise attack to intercept. With this new intelligence level the reaction player can now do a few things to try and stem the enemy tide in battle.

Reaction Movement

Now that the Intelligence level is anything other than surprise attack [which would allow no reaction moves whatsoever], the Reaction player now designates a single in-supply HQ in order to activate units to move into battle. The designated HQ must be within range of the declared battle hex. This range is just counted as hexes, and nothing can block that hex trace. This is one of the few times that there are absolutely no hindrances to a hex trace. Figure 12 shows that the reaction player is going to choose South Pacific HQ as the reaction HQ. It has a range of 7 that can reach from hex 4423 all the way to 3820 where the battle will soon commence.

Figure 12: South Pacific activates because the battle hex is within its command range, and can now command units to react into the battle hex.

The activated HQ can command units to react into the battle hex, and only the battle hex, the number of which is as follows: the HQ’s efficiency rating, in this case 1 (the red and white number in the bottom right of the HQ chit) plus the Operations value of the Offensives card used in order to conduct the combat in the first place, which was a 3 in this example. Figure 13 indicates that the HQ activates 2 naval units in its command range (green lines) which will move (red lines) into the battle hex.  A further 2 units could theoretically be activated for a total of 4, but the allies don’t have anything else in range to activate.

Figure 13: South Pacific HQ commands the Miss and US Asia naval units to join the fray, it might be folly, but in war there’s always a chance.

As a side note, some of the reaction cards are ‘Counter Offensive’ cards, which function similarly to a mini regular offensive and allow you to do a bit more than just adjusting the intelligence level and reacting a few units into the fray. After the reaction moves the Allied stack in, the battle hex consists of 3 naval units and the 1 MAW air unit, pictured in Figure 14. This might not seem like an awful lot, and it isn’t, but the Allied player is counting on dice rolling to help swing the tide of battles.

Figure 14: Allied units have finished their reaction moves and now we are ready to total combat strengths and let the battle commence.

Combat Resolution

Now that all moves have been completed by both sides; the combat strengths of all participating units are totaled by each side. So let’s take a look at Figure 15 below, which has all of the units spread out in order to see the totals. The far left number on each counter is the combat value and you just add them up, remembering to do half values for any air units participating that used their extended range. As you can see, sometimes you might need a calculator on hand, because a big offensive can quickly have a staggering combat total.

Figure 15: Units spread out in order to calculate combat strength totals: 87 for the Japanese, 27 for the Allies.

The Japanese player has nearly 3 times as much combat strength as the Allied player, so the Japanese player looks to be in great standing and on the brink of inflicting some serious damage to the Allied fleet. The best that the Allies can hope for is that the Japanese player rolls poorly and has the combat strength reduced and then be able to trade blows. The Japanese player has a combat total of 87 compared to the Allies meager 27. Each side then rolls a 10-sided die and then consults the player aid in order to determine the results. Figure 16 (below) shows the two die rolls, both of which aren’t great and the results seem especially dismal for the Allies.

Figure 16: Japanese player rolls a 5, and the allied player rolls a 2, these numbers are modified and then compared to the CRT.

The combat results table shows the dice roll result, a short series of dice roll modifiers (DRMs) and then the results factors by which you multiply your total combat strength. So in Air Naval combat you will either be fighting at full, or less than full strength. In ground combat, which will follow in a later post, it’s possible to fight above your printed combat strengths, but for Air Naval you’re just hoping the roll doesn’t hurt you too much. There aren’t all that many DRMs but some of them can be very significant depending on the stage of the game. Being able to utilize them can really help you to maintain full combat efficiency, so watch out for situations to be able to take advantage of them.

The Japanese player rolled a 5, and the allied player rolled a 2. Looking at the DRMs in Figure 17 there are no modifiers to either roll, because it’s 1942, the intelligence level is intercept, and there are no modifiers specified on the Offensive Event Card. The results are compared to the CRT, also in Figure 17, the Japanese units will fight at half strength, and the Allies at a meager quarter strength.

Figure 17: DRMs and CRT for Air Naval combat, there’s not a lot but they’re powerful if you can harness them.

Assigning Damage

Empire of the Sun comes with a printed Combat Factor calculator on the back of the player aid card, so you don’t need to worry about your mental mathematics skills. I really enjoy the chart just because it takes a small edge off and helps to speed the combat along. You won’t be taking a calculations break very often in this game.

Figures 18 & 19 shown below highlight the combat totals on the left and a series of columns with the 0.25, 0.5, 1, 1.5, and 2 times multiplied combat factor totals. The Allied player will be able to assign a measly 7 points of damage, and the Japanese player will assign 44 points of damage. Damage is assigned by the opposing sides, so the attacker decides which defending units are hit and vice versa.

Figure 18: Japanese Combat Factor Calculator total 87/2 = (rounded up) 44.

Figure 19: Allied Combat Factor Calculator total 27/4 = (rounded up) 7.

When assigning damage to units, a player has to be able to meet the defensive value [or hit points] in order to flip the counter over to the reduced side. With this in mind, the Allied player has 7 damage to assign, as all of the Japanese units have a defensive value higher than 7 no lasting damage is done. In effect, that seven damage represents superficial damage with no lasting effect to the units.

The Japanese player however assigns 44 points of damage and does so within a few constraints. Units may only be destroyed once EVERY unit has been reduced. So, you have to reduce every unit if possible, and then with the excess damage if you can meet the defensive values again, then you can start to destroy units.

Figure 20: The Japanese player reduces all Allied units then destroys the air force unit. The Allied player is unable to reduce any Japanese units.

The Japanese player has enough damage points to assign such that he can reduce every Allied unit with 12 damage points to spare. The options to consider are destroying the 2 US Asia ships or destroying either one of the 1MAW air unit or the Miss. The Japanese player decides to destroy the air force in order to eliminate the ZOI they project and leave the Allied fleet more vulnerable (Figure 20). As a note, if on the attack roll a natural 9 had been rolled a ‘critical’ hit is obtained in which the rules for damage assignment may be broken. A critical hit means that enemy units may be assigned damage such that they are destroyed whilst full strength units still remain in the combat hex. Furthermore, a critical hit scored by a side with not enough strength to inflict a step loss automatically gets to inflict one step loss anyway.

Offensive Conclusion

Now that the damage has been assigned a winner is determined, and it’s as simple as counting the surviving attack strength of all of your units that contributed to the combat. Air units fighting at half strength because of extended range still only contribute half their combat strength to this calculation. Pretty obviously, the Japanese player ‘wins’ this combat. However, as this was purely an Air Naval combat there are no ground units to take the island from the allies, and therefore the Japanese fleet must fall back. Control of the battle hex remains with the reaction player if there are no offensive ground units at the end of the battle. With this in mind, the Japanese player in Figure 21 conducts post battle movement and moves a carrier and two ships to defend Truk whilst the rest of the Fleet returns to the Home Islands to protect mainland Japan. For this post battle movement, the units have the same movement allowance as per the offensive card played, in this way it’s very hard to commit a naval fleet and then have it get stranded for example; the ocean is a big place with a lot of room to maneuver and slip away from a sticky situation.

Figure 21: The Japanese player must pull back as they are unable to land any troops in the Admiralty Islands. They may move the same movement allowance as allowed per the Offensives Card.

Phew! That was a lot. But we got through it, with hopefully more answers than questions. Tactically speaking, Air Naval combat is extremely important, you’ll use it to soften up targets before conducting amphibious assaults, or for just destroying important carrier fleets as well as positioning and many other reasons. In the face of overwhelming odds the Allies somehow held onto the Admiralty Islands, albeit with grossly depleted forces. So even a massive stack of units is not invincible, nor unstoppable and the dice rolling can make all the difference, had the Japanese player been fighting at ¼ strength and the Allied player at full strength then the damage assignment would have looked very different. Many of the valuable and basically irreplaceable Japanese units would have been reduced which would have been bad in the long run. The Allies get a healthy amount of replacements nearly every turn so they can ‘weather the storm’ a little bit more with combat casualties and reductions.

In the next few articles we’ll take a look at ground combats, amphibious assaults, and then how they all work together. This can seem very complicated diving straight in, but looking at the two phases separately will help us break it up. Then we’ll just combine them (Air Naval and ground) into one massive combat to see how those function and the rules that carry over between the two combats.

Thanks so much for reading and feel free to ask any questions and I’ll try to answer them.

-Alexander Klein [Rules version 3.0]

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8 thoughts on “Empire of the Sun Rules & Tactics Intro: Air Naval Combat

  1. This is absolutely amazing. As an owner of this incredible-but-difficult game, I’ve never had such great trouble absorbing a game as I have with Empire of the Sun. I find this article to be of immense help, thank you very, very much!

    • Thanks for reading and your feedback! I absolutely love this game, Mark Herman has created a true masterpiece. That said, it has a very steep learning curve, and I find many people who own the game but have never played because of how dense it! So I started writing these to help take the sting out of the rule book a little and walk through some of the steps in the game. We just picke dup C3i #30 which has ‘South Pacific’ in it, and I’d highly recommend that as it’s very similar from a mechanics standpoint but not nearly as daunting from a scale standpoint.

      • Thank you for the advice as well. I’ve also heard very nice things about South Pacific and with your recommendation, I will certainly seek it out to help with digesting EotS. Looking forward to further articles on this beast!

  2. Thanks for this great article. As a side note to the guys feeling intimidated with EotS: starting with a one-year-scenarios helps tremendously getting the strategic part of the game to bite size, e.g. 1943. There are a few articles for the strategic part, too.

  3. What an interesting series of articles. I’m beginning to think that I could one day get to play EotS after all! Thanks very much for all your hard work and dedication – great effort!

  4. Hello Alex, and thank you for this very interesting article.
    My question is : on exemple figure 7 & 8, you talk about the aircraft range of 2.
    So, this aircraft is supposed not to have enough range. But we saw just before that the OC value is 3.
    The range of the aircraft isn’t supposed to be 2 times 3, and not only 2 ?

    Hope my english is good enough 🙂

    Stef the froggy.