Maury served in the Mexican–American War at the Battle of Cerro Gordo, and suffered a painful wound that almost resulted in the amputation of his arm.

His gallantry in this event prompted the citizens of Fredericksburg and the Legislature of Virginia to honor him with a special presentation sword.

[1] Maury then returned to active field duty with the Mounted Rifles, serving in the Oregon Territory, then on the Texas frontier.

When the Civil War began, Maury was the Assistant Adjutant General in the New Mexico Territory, based in Santa Fe.

Hearing the news of the firing on Fort Sumter, he resigned from the United States Army and travelled back to Virginia.

With the conclusion of the Civil War, Maury came home to Virginia and established an academy in Fredericksburg to teach classical literature and mathematics.