Militia in Manor Lords is cheap to raise and expensive to lose. Every casualty is a worker who was also doing a job, so the goal is not just winning fights but winning them without losses.
Spears are the entry point. One iron ore becomes one slab becomes one spear, which makes a 100-iron deposit worth 100 armed men. A spear militia held in a defensive stance, standing still and facing the charge, clears raiders and bandit camps with no losses at all. Hold the line until every attacker has committed, then flip to aggressive.
Armour decides close fights, and armour is gated by housing tier: tier-1 plots supply helmets, tier-2 adds gambesons, tier-3 adds chainmail. A fully mailed 36-man regiment needs roughly 18 tier-3 plots behind it, which is why the food and variety work above is also military work.
Two structural notes for the first year. Create all six militia groups before building your first manor house, since the manor's retinue otherwise eats a slot. And hire dangerous mercenary companies before contesting a region. If you don't, the AI will, and you may face them instead.
Lossless bandit clearing with spears
Warfare & Militia
Stand still, defensive stance, face the charge. Once every bandit reaches the line, flip aggressive.

A tired regiment loses fights an identical fresh one wins
The manor spawns a retinue that eats a slot. You only need to CREATE the groups, not fill them

If you don't hire them, the AI will, and you can end up facing 10–15 regiments in a single battle.
The contract fee isn't one-time. Disband a company right after the fight to stop the drain.
Running out of local ore stalls all tool production until a new territory covers it. Line up capacity there first.

Turning up under strength turns a free influence payout into casualties you cannot replace, since every militiaman is a worker who was also doing a job.

Depending on settings, the first level on five plots hands you gear for about 20 spearmen. A whole bandit-clearing force before you build any arms industry.
That single payout covers more than a mercenary company's monthly fee, which means the first camp can fund the clearing of the second without you fielding your own people again.
They hold instead of shooting, so archers parked behind your line contribute nothing once the lines meet. Angle them for a flank or open ground and they work; place them directly behind spearmen and they idle.
Read all 19 Warfare & Militia tips in the field book →
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Food & Population
Armour is gated by housing tier, and housing tier is gated by food variety. Militia strength starts in the granary.
Trade & Wealth
Mercenary companies and imported weapons are paid for in regional wealth.
Farming & Fields
Every casualty is a worker who was also farming. The cost of a fight is measured in next year's harvest.