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Hearts of Iron IV
Hearts of Iron IV
1.19.0|Jun 10, 2026
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Thunder at our Gates | Patch Notes (1.19.0)

5/5 Game-Changing

Major expansion adds new Focus Trees for Australia, Siam, and the Dutch East-Indies alongside the game-changing Army HQ and Ship Captain systems.

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Key Changes

  • 1New Focus Trees for Australia, Siam, and the Dutch East-Indies
  • 2Introduction of the Army HQ system for field-deployed generals
  • 3New Ship Captain system with medals and promotion to Admiral
  • 4Special Forces Doctrine system and Regimental Support row in Division Designer
  • 511 unique HQ support companies and 5 new commander abilities
  • 6Japanese Home Islands airzone split into three distinct regions
  • 7Pearl Harbor raid success chance rebalanced and tied to focus progression
  • 8Major AI improvements for carrier management and North African defense
  • 9Performance optimizations including multi-core trade system support
  • 10Over 700 typos fixed and multiple crash/OOS resolutions

All Changes

🏳️Factions(5)

  • newAustralia: Added new Focus tree and a new Democratic Election system
  • newSiam: Added new Focus tree
  • newThe Dutch East-Indies: Added new Focus tree
  • changeUnited Kingdom: Reworked the Fortify East Asia focus tree branch
  • newPortugal: Added focuses regarding Asian colonies to the colonial branch

⚙️Gameplay Systems(7)

  • newArmy HQ: Introduced Army HQs allowing generals to be deployed into the field to provide support to their armies
  • newArmy HQ: Added 11 unique HQ support companies and 5 new commander abilities unlocked through them
  • newShip Captains: Added Ship Captains to naval vessels with the ability to grant medals and promote them to Admirals
  • newSpecial Forces: Added new Doctrine system for Special Forces
  • newDivision Designer: Added a new row for Regimental Support to the Division Designer with 12 new support companies
  • newDispersed Operations: Added Dispersed Operations doctrine focusing on logistics and reducing enemy air power effects
  • newShips: Added several new critical states for ships including Leaking Pressure Hull and Reactor Coolant Loss

⚖️Balance(9)

  • nerfPearl Harbor: Pearl Harbor raid base success chance reduced
  • buffPearl Harbor: Pearl Harbor success chance is now improved by the 'Form the Kido Butai' focus
  • changeJapan: Split the Japanese Home Islands airzone into Northern, Central, and Southern Japan
  • buffArmour: Continuous Offensives: All armour additionally gains +10% breakthrough
  • nerfSelf-Propelled Vehicles: Shoot and Scoot: All three SP categories max organisation reduced from +10 to +5 and recovery rate from +20% to +15%
  • nerfTank Destroyers: Shoot and Scoot: Tank destroyers' hard attack reduced from +15% to +5%
  • nerfSupport Artillery: Integrated Support Batteries: Support artillery soft attack nerfed from +10% to +5%
  • nerfArmy: Breaking Out: Army-wide soft attack nerfed from +20% to +15%
  • changeCommand Power: Command powers daily costs now scale with amount of battalions affected

🤖AI Behavior(4)

  • changeUnited Kingdom: Improved UK competence at defending Egypt and attacking Tripoli and Iraq
  • changeItaly: Italy will use its airforce more in Africa and maintain a stronger presence in North Africa
  • changeGermany: Germany will produce slightly more light tanks and fewer trains overall
  • changeAI: AI is now better at filling carriers with airplanes, including reusing old equipment

🎨Visuals & Audio(4)

  • newAirplanes: Added 50 new and revamped airplane models
  • newTanks: Added 21 new and revamped tank models
  • newArmy HQ: Added 14 Army HQ commander models including 3 generic cultural variants
  • newAudio: Added 6 new Music Tracks

🚀Performance & Stability(3)

  • fixPerformance: Trade system now utilizes more CPU cores for better performance
  • fixPerformance: Reduced save file size from provinces
  • fixStability: Fixed multiple crashes occurring on MacOS during peace conferences and relation updates

🐛Bug Fixes(4)

  • fixGeneral: Fixed 700+ typos across the game
  • fixExploits: Fixed exploit where players could gain more manpower by leaving and rejoining a faction
  • fixGameplay: Fixed an issue where subjects could impose a naval blockade on their overlord
  • fixGame Rules: Fixed various issues with decolonization game rules for Asia, Africa, Oceania, and the Americas

📅Coming Soon(1)

  • changeAustralasia: The formable Australasia nation is planned for inclusion in patch 1.19.2

Summary

Thunder at our Gates Expansion

This major update introduces significant content for the Pacific theater, featuring full Focus Trees for Australia, Siam, and the Dutch East-Indies. A new Army HQ system allows players to deploy generals directly onto the map to provide localized buffs and support through 11 unique HQ support companies. Naval gameplay is also deepened with the introduction of Ship Captains, who can earn medals and eventually be promoted to Admirals.

Gameplay & Balance Overhaul

Beyond the new content, the patch introduces a Special Forces Doctrine system and a new Regimental Support row in the Division Designer. Balance changes target the Pearl Harbor raid, command power scaling, and a massive rework of the Japanese Home Islands airzones. The AI has been significantly tuned to better handle North African defense, carrier management, and production priorities for major powers like Germany and Italy.

Technical Improvements

Performance has been optimized with multi-core support for the trade system and reduced save file sizes. Over 700 typos have been corrected, and numerous stability issues, including MacOS-specific crashes and multiplayer out-of-sync (OOS) errors, have been resolved.

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