Why did the U.S. Army increase in size during the Second Seminole War?

The U.S. Army increased in size during the Second Seminole War primarily due to the intense, prolonged nature of the conflict and the simultaneous need to manage the expansion of the western frontier.1

While the regular army had been reduced to 6,127 men by 1821, the military faced significant challenges in Florida as the Seminole people resisted forced relocation under the Indian Removal Act. The Seminoles utilized effective guerrilla tactics, which stymied initial U.S. efforts to subdue them and resulted in heavy casualties for government forces.213

To address these difficulties and the broader requirements of frontier security, Congress authorized an increase in the army's authorized strength to 12,577 men in 1838. This expansion provided the necessary manpower to sustain the long-term military campaign until the conflict ended in 1842, after which the army was again reduced in size.1