At the Battle of Borodino in September 1812, Captain Crozet was taken prisoner, but released in 1814 and returned to duty in the French army.

[3] Napoleon abdicated in April 1814, but returned to power about a year later, was defeated at the Battle of Waterloo on June 18, 1815 and surrendered about a month later.

[5] Almost immediately after arriving, Crozet began work as a professor of engineering at the U.S. Military Academy at West Point, New York.

He also used the "Elementary Course of Civil Engineering", translated from the course of M. J. Sganzin at the École Polytechnique, designed several of the buildings on the campus, and published A Treatise on Descriptive Geometry.

[8] He resigned from his duties at West Point, and brought his wife and two children (a boy and a girl) with him to live in Richmond, Virginia.

Typical of his many projects of this nature was the Chesterfield Railroad, the first in Virginia, the plans of which he examined before Board of Public Works funds were approved.

He left office in 1843 after losing support of canal owners when he correctly forecast the future advantages railroads would hold for Virginia.

[9] Ten years later, he and at least two much younger engineers boarded with plantation owner John T. Cocke in Albemarle County, Virginia.

Dug a decade before the invention of dynamite it was considered to be an "engineering wonder of the world" and was less than a half-foot (15.2 centimetres) off perfect alignment, as construction had proceeded from either end.

During the American Civil War, Confederate General Thomas Stonewall Jackson, a former instructor at VMI, used Crozet's tunnel to transfer his "foot cavalry" (comparable to a rapid deployment force today) from the Shenandoah Valley to the east side of the Blue Ridge quickly, to the puzzlement and consternation of Union military leaders.

Crozet died in January 1864 at the residence of his daughter and son-in-law, as the Confederacy was losing the Civil War, but more than a year before its defeat.