Reinforce moves troops from one town to another. This can be useful for defense or just to reallocate troops to a different town.
Reinforce is used as a defense to put more troops into a city that is getting attacked, so that it can win the battle.
You can reinforce your allies' towns by having them check the "Allows troops of allied members to garrison your current city" box in them Embassy (Only level 1 needed, but the higher the level, the more reinforce waves you can receive, 1 more per level).
NOTE: Troops will use food of whatever city you put them up. Make sure you don't exceed your production in food. NOTE: If reinforcing an alliance member, these troops can only DEFEND. They cannot be used to attack.
- It is important to remember that in most cases the defending troops that are in the city and the ones in the embassy are stronger than the troops attacking the city. So, 100k archers goes along way in most cases. Although its also important to remember those troops need to be fed and if they die from starving or even getting attacked, you lose your troops. In Age II, troops do not starve.
Reinforce can also be used to save troops. If your beacon tower and informatics are high enough level, you can see exactly when an attack will hit your city, and you can also see what troops the enemy is sending. If you can't defend against the attack, you should click on another city or a valley that you have and click reinforce. Use all your troops with a random hero and bring along as much gold and resources you can. Then, when the enemy leaves, you can recall your hero. On servers where plundering player cities is disabled, it is enough to "close gates" in the rally spot (by unchecking the box "open gate to fight"). That way, your troops will not take part in the battle, and can not be killed by the enemy troops.