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All infantry march faster.
—In-game description

Military Drummers is a technology in Age of Empires III that can be researched by European civilizations at the Arsenal once the "Advanced Arsenal" Home City Card has been sent (except for the Swedes). Once researched, it increases the speed of all infantry by 10%.

For the United States, if the "Knowlton's Continental Rangers" card is sent, this technology increases the speed of the Spies by only 2%.

Arsenal technologies
InfantryInfantry Breastplate · Counter Infantry Rifling · Socket Bayonet · Flint LockA · Paper CartridgeA · Military DrummersA
CavalryCavalry Cuirass · Ranged Cavalry Caracole · PillageA
ArtilleryGunner's Quadrant · Heated Shot · Professional GunnersA · TrunionA · Incendiary GrenadesG
A requires the Advanced Arsenal Home City Card
G only available to civilizations with Grenadiers