Willard served in the regular service until the outbreak of the Civil War, rising to the rank of captain.

At the outbreak of the war Willard was unwilling to give up his regular commission and so he missed any chance to command a regiment of volunteers.

His raw recruits did not distinguish themselves in the Battle of Harpers Ferry, in which they fell apart under fire during the fighting on Bolivar Heights.

[3] When the garrison was surrendered to Stonewall Jackson by Col. Dixon S. Miles, Willard and his men became prisoners of war.

Willard testified before the military commission that investigated the surrender of Harpers Ferry and was critical of the conduct of Miles.

Reaching Gettysburg, Pennsylvania late on July 1, Willard's command camped along the Taneytown Road behind the Round Tops.

Late on July 2, when Maj. Gen. Winfield S. Hancock had been placed in charge of the Army's endangered left flank, he sent back to his II Corps for reinforcements.

Gen. William Barksdale, who had captured the Union position at the Peach Orchard and then pressed forward toward Cemetery Ridge.

The New Yorkers recovered abandoned Union guns, but came under heavy fire from Confederate artillery after crossing Plum Run.

[9] Camp #154 of the Sons of Union Veterans of the Civil War in Albany, New York is named for Willard.