The Field Hospital heals by 20 hit points per second in a radius of 24 (the same radius as the Missionaries Unction Aura), and will only heal units not currently being attacked, including losing hit points over time such as the Minuteman, Irregular, and Warrior, though it will heal the last three once they reach 1 hit point up to 11, which they will lose again back down to 1 over time. They will also not heal units engaged in attacking the enemy, though with skill expensive wounded units can be kept constantly retreating, then returning to the front after being healed. It can only be built by Surgeons sent directly from the Home City, or trained at a Church, or Mosque after the Master Surgeons card is sent by the Portuguese, Germans, Ottomans, and Russians. The Chinese and Indians can ship Surgeons from their Consulate with a British ally selected. They are primarily a defensive structure, placed behind the front lines and protected by walls.
Only four Field Hospitals may be built, so it is important to choose an appropriate strategic location. Against human opponents that focus fire efficiently they are fairly useless, since there will rarely be wounded. Against less efficient human players, or the AI, however, many resources can be saved by healing the wounded.
A field hospital is often the first stop for a wounded soldier. It provides treatment at the scene of battle to stabilize wounded people enough so that they can be escorted away from the battlefield to receive further treatment. Napoleon was the first leader to have dedicated medics on the field of battle; George Washington had litter-bearers on the field during the Revolutionary War.