War is a vital part of humanity because sooner or later you and another empire will be at odds. You might be able to settle it with words, but sometimes steel is the only answer.
In wartime, you have units that make up your combat force. During battles, you can call in reinforcements to turn the tide of battle. To do this, you will first need to research Organized Warfare Technology.
Related: How to Force a Surrender in Humanity
To bring these reinforcements into battle, all you have to do is move the units into the battle and they will join. This can allow you to trick enemies into attacking a weaker force only to bring more units into a surprise attack. What makes reinforcements so valuable is that they can act like existing units on the first round of combat.
As a general rule, you can only use units that are on the tactical map in battle. With reinforcements, you will be able to summon units outside the tactical map. If the number of units added is too large for the tactical map to hold, it will expand to accommodate the new units. The battle round limit will also increase with the addition of new units.
For more information on Humanity, check out How to Sponsor Freelancers into Humanity and How to Get Rid of a Town in Humanity on Pro Game Guides.
