Hearts of Iron IV: Beginner-to-Advanced Guide

How Hearts of Iron IV plays in 2026: the economy, production, divisions, supply, combat and planning, plus a first campaign plan, the DLC lineup and the mistakes that lose most new players' wars.

Researched September 2026 — current as of patch 1.19.3 (September 2026, the last Thunder at Our Gates balance patch). Live games change; check the linked sources if something differs.

Quick Start

1. The game is won in 1936-1939. What you build before the war decides the war. Spend the peacetime years on factories, research and a sensible army, not on a huge military you can't supply.
2. Build civilian factories first, then military factories. Civilian factories build everything else. A common rule is to build civs until about 1938 (earlier if you're under threat), then switch to mils.
3. Always keep all research slots busy. An idle slot is lost time. Industry, electronics/computing and your core land doctrine come first.
4. Infantry equipment is the most important production line. Keep several factories on it the whole game.
5. Watch supply. Troops beyond your supply network lose organization and strength. Check the supply map mode before any offensive.
6. Use battle plans, but check them. Front lines plus offensive arrows let the AI micro your divisions. Watch them and step in when a push stalls.
7. Start with a forgiving nation. The USA, the UK, Germany or Italy (on a lower difficulty) teach the systems without instant pressure.
8. Pause often. Space pauses. The game rewards stopping to check production, research and supply.

The DLC Lineup (as of September 2026)

Every DLC comes with a free patch that everyone gets. Patch 1.17 (with No Compromise, No Surrender) reworked factions, doctrines and naval supply, and added Coal and factory energy to the economy; the expansion itself adds expanded faction rules and alliance goals. Patch 1.19 (with Thunder at Our Gates) reworked the division designer and Army HQs and changed Special Forces doctrines. Paradox has also announced a Romania DLC ("releasing soon" per the September 2026 Studio Gold Update, no date yet) and a Quality of Life update aimed at reducing clicking. The next major expansion has been delayed for quality, and September 2026 Dev Corners are exploring military production, industry location and Great Depression changes, all subject to change.

What to buy first: The older core expansions (Together for Victory, Waking the Tiger, Man the Guns, La Résistance, No Step Back, By Blood Alone, Arms Against Tyranny) add the systems most players consider essential, such as naval rework, officer corps and air/spy mechanics. Country packs mostly add focus trees, so buy them for nations you want to play.

Core Systems

Political power, advisors and focuses

• Political power (PP) pays for national focuses, advisors, laws, decisions and ideas. Early PP usually goes to economy laws (Partial Mobilization and beyond) and advisors that give research or construction bonuses.
• National focuses take a set number of days each. Queue the ones that give research slots, factories, or claims/cores first. Research-slot focuses have beaker icons.
• Stability and war support gate laws, decisions and production efficiency. Low stability hurts factory output. Low war support blocks mobilization laws.

Industry and construction

Rules of thumb:

• Build in states with free building slots and good infrastructure. Construction is faster where infrastructure is high.
• Consumer goods eat part of your civilian factories. Economy laws that lower them are among your best early PP spends.
• Production efficiency ramps up over time on a line. Don't keep switching what a factory makes, and don't spread 1-factory lines everywhere.
• Resources: Oil, Rubber, Steel, Aluminium, Tungsten, Chromium and Coal. Missing resources cut production. Coal (added with the 1.17 economy changes) powers your factories: powered civilian factories output 5 instead of 4, military factories 4.5 instead of 3.5, and dockyards 2.5 instead of 2, so don't ignore it. Trade costs civilian factories, so research Excavation techniques for more domestic output, and only import what you really lack.

Research

• Keep every slot running and use research bonuses from focuses and advisors on the tech they boost.
• Researching ahead of time (before the historical year) takes much longer. It's usually only worth it for key items like Basic Machine Tools and early industry.
• Early priorities for most majors:
  1. Industry: production and construction techs, Excavation
  2. Electronic Engineering: computing techs that speed all research
  3. Infantry weapons and support equipment
  4. One land doctrine, picked to fit your plan
  5. Air: fighters and close air support or tactical bombers, depending on the war

Divisions

A division template is a set of battalions (up to 25) plus up to 5 support companies. Changing templates costs Army Experience. At the time of writing, the wiki lists 5 XP to add, remove or replace a battalion, 20 XP for each new regiment category, and 10 XP per support company change. Support companies don't add combat width.

Starter templates (common community picks; 1.19's division designer rework changed some numbers, so check stats in-game):

Combat width limits how many divisions fight per battle, depending on terrain. Keep templates at widths that fit common terrain rather than making one giant division. Look at the terrain combat width tooltip in-game before settling on a width.

Supply and logistics

• Supply flows from your capital by rail to supply hubs, then out to divisions. Hubs need a railway connection and are limited by infrastructure.
• Trucks (or horses in the early game) carry supply from hubs to units. Motorized hubs cost trucks, so keep a production line of Trucks going in wartime.
• Naval supply runs through ports and convoys. Invasions and overseas fronts need convoys and naval control.
• Before a big offensive, check the supply map mode. Red means your divisions will starve. Build railways and hubs behind your front as you advance, and repair captured rail.

Combat basics

• Organization runs out first, then units retreat. Strength is the physical damage. A division with high strength and no organization is useless.
• Attack vs defense: A unit's soft/hard attack is compared against the enemy's defense (when defending) or breakthrough (when attacking). Piercing vs armor decides whether tanks take reduced damage.
• Air superiority gives big bonuses. Close air support devastates enemy divisions if you own the skies.
• Terrain and rivers penalize attackers. Attack across open plains, not across major rivers or into mountains.
• Encirclements destroy divisions outright. Armored spearheads plus holding infantry are the classic way to win.

Battle plans

1. Draw a front line along the border.
2. Draw an offensive line where you want to push.
3. Assign an army with a field marshal (planning bonus builds up the longer you wait before executing).
4. Hit execute, and watch it. Plans often attack piecemeal into forts. Manually target weak points with your tanks.

A First Campaign (USA or UK, default difficulty)

1. Day 1: Queue research in all slots, set construction to civilian factories, and start focuses that give industry or research.
2. Spend PP on the economy law and one research or construction advisor.
3. Production: infantry equipment, support equipment, artillery and fighters. Add convoys if you're a naval power.
4. 1937-1938: switch construction to military factories. Upgrade economy and conscription laws as war support allows.
5. Set templates before the war, while XP is easiest to spend.
6. 1939 onward: Hold with infantry, push where you have supply and air superiority, and keep production of infantry equipment and trucks running.

Nation Notes

Common Mistakes to Avoid

• Military factories too early. Without a civilian base you'll be out-built by 1940.
• Idle research slots. Check them every time you pause.
• Ignoring supply. Pushing past the rail network throws away your offensive.
• Changing production lines constantly. Efficiency resets every time.
• Over-sized or odd-width divisions that waste width and cost more.
• No air force. Enemy air superiority shreds divisions and supply.
• Never checking plans. The AI will throw divisions into forts and rivers.
• Trading for everything. Each trade costs civilian factories. Research Excavation and build synthetic refineries for rubber/oil where you can.
• Forgetting Coal. Unpowered factories produce noticeably less; secure coal before you scale up industry.

Advanced Tips

• Micro your tanks. Plans are fine for infantry. Hand-steer armored divisions into encirclements.
• Use the planning bonus. Let plans build up bonus before you execute, but don't let it sit so long that the enemy entrenches.
• Naval invasions need naval supremacy and a port nearby. Take a port on day one of the landing.
• Spend Army XP wisely: templates first, doctrine choices next.
• Watch for 1.19 changes. Army HQs, the division designer and Special Forces doctrines changed in 1.19, and 1.19.3 halved supply use for armored HQs. Older YouTube templates may no longer be the best choice.
• Factions (since 1.17) have rules and goals. If you lead one, set rules that help your war aims, and use members' industry instead of doing everything alone.
• Ironman for achievements. Achievements only unlock in Ironman mode, and some game-rule changes disable them.

FAQ

What's the latest HOI4 version? Patch 1.19.3, released September 17, 2026. It was the last patch specifically targeting Thunder at Our Gates, adding a secret Australia path, late-game Siam and Indonesia content, and balance changes from the summer Open Beta.

What's the newest DLC? Thunder at Our Gates (June 11, 2026), a Theater Pack with Australia, Siam and Indonesia plus Military HQs and Ship Captains. A Romania DLC has been announced.

Which DLC is essential? Most players say the older expansions (Waking the Tiger, Man the Guns, La Résistance, No Step Back, By Blood Alone). After that, buy packs for the nations you want to play.

When should I switch from civilian to military factories? Usually around 1937-1938 for majors. Switch earlier if a war is coming sooner.

Why are my divisions losing organization and not attacking? Usually supply (check the supply map), fighting across rivers or bad terrain, or enemy air superiority.

How do I get achievements? Play on Ironman with achievement-compatible game rules. The game-rules screen tells you if a setting disables achievements.

Sources

• Steam News — Hearts of Iron IV (Patch 1.19.3, Dev Corners, Romania DLC)
• Hearts of Iron 4 Wiki — Downloadable content
• Hearts of Iron 4 Wiki — Patches
• Hearts of Iron 4 Wiki — Thunder at Our Gates
• Hearts of Iron 4 Wiki — No Compromise, No Surrender
• Hearts of Iron 4 Wiki — Division designer
• Hearts of Iron 4 Wiki — Resources
• Hearts of Iron 4 Wiki — Beginner's guide