Battle Armor is a technology that is unique to the Royal Naboo, and can be researched at the Fortress in Tech Level 3. It costs 225 Food and 200 Carbon, and gives +25% Hit Points to all Fortress units except the Air Cruiser. It was a requirement for Shielding, before the latter's effect was included in the Elite Royal Crusader upgrade in the expansion.
This technology makes the player's Bounty Hunters, Royal Crusaders and Cannons sturdier, giving them an edge in combat.
This technology is the one of two unique improvements for Cannons (along with Taxation), which become better, than for other civilizations.
"The only Tech Level 3 technology available from the Fortress, Battle Armor grants a bonus to the hit points of all units produced at the Fortress, including Bounty Hunters, your civilisation's unique unit, and Cannons."
—Manual description