|UNSC Field Armory|
The Field Armory allows you to research upgrades for various parts of your forces. Adrenaline makes your infantry units move faster. Reserves allows your units to train faster. Reinforcements allows your max population to increase. You can also upgrade your M202 turrets so that they have multi-barrel configurations, so that they look like twin or quad .50s. The last upgrades can improve the hero unit's leader power, which can give three additional MAC gun shots for Captain Cutter, almost quadruple the amount of bombs and target area of Sergeant Forge's Carpet Bomb, and increasing the effect time of Professor Anders' Cryo Bomb as well as making it so that it smites more aircraft from the sky during the initial freeze.
Strategically speaking, it is better to build a Field Amory in the beginning to acquire the desired upgrades and then to remove it in order to raise a different facility. The upgrades remain, even as the Field Armory is gone.