As of this guide, Thunder at Our Gates is the series' most recent Theater Pack, released June 2026. It doesn't rewrite the whole game the way a major expansion does, but two of its additions show up in any game, wherever you play.
What New Content It Adds
The pack splits its additions into two clearly separate blocks: content specific to three Pacific nations, and two mechanics that show up wherever you play, whether or not those nations are among your favorites.
Nations: Australia, Siam, and Indonesia
Australia, 
Siam (Thailand) and 
Indonesia get a proper focus tree with real substance for the first time — until now that corner of the map was mostly empty. The pack is part of Expansion Pass 2 alongside No Compromise, No Surrender — also centered on the Pacific — and Peace for Our Time, which instead focuses on Czechoslovakia. Since it's recent content, there's still not much written about these routes: if the region interests you, this is a good moment to learn them before they turn into well-trodden ground.
Mechanics: General Headquarters and Ship Captains
The 
Army General Headquarters is the addition that actually matters outside the Pacific: a brand-new command layer between your divisions and the top brass that didn't exist before. Each General Headquarters gets assigned to a specific army group and provides coordination and logistical support bonuses that used to only apply at the full theater level — in practice, running several fronts at once costs you less as long as you spread your General Headquarters between them properly. Like regular generals, they gain experience and can develop their own traits over time, so it pays to keep them fixed on the same army group instead of rotating them without reason.
Ship captains add a similar command layer, but at the individual ship level instead of the whole fleet: each captain carries their own traits — better gunnery accuracy, improved detection, more damage resistance — and can be reassigned between ships as long as they aren't mid-operation. It's the difference between treating your fleet as one uniform block and optimizing it ship by ship, which matters a lot more the bigger and more varied your navy gets.
Is It Worth Buying?
If the Pacific doesn't appeal to you, the three new nations won't pull you in. But Army General Headquarters touches any game, so the pack isn't pure decoration for the rest of the world. If Australia, Siam or Indonesia also interest you, the purchase justifies itself.