Károly Zágonyi (19 October 1822 in Szinyérváralja, Hungary – around 1870)[1] known in the U.S as Charles Zagonyi, was a former Hungarian military officer who served in the American Civil War as an aide to John C. Frémont and commander of his bodyguard at the rank of major, effective September 19, 1861.

Zagonyi "personally selected the matched bay mounts" and designed the dark blue uniforms and hats of Hussar style.

The charges proved costly in terms of casualties and the major lacked the forces to hold the city of the Union after dark.

Zagonyi's charge would become famous, but his refusal to give credit to other attached forces alienated many fellow officers.

Stonewall Jackson and his Confederates outmaneuvered and outfought Frémont's much larger force during the Valley Campaign.

Following this final Frémont debacle, General John Pope was assigned to command all of the U.S. troops in northern Virginia.