Born in Sinsheim, Baden, Germany, Sigel graduated from the military academy at Karlsruhe in 1843 and became a key military leader during the 1848 revolutions. He emigrated to the United States in 1852, living first and New York, and then St. Louis. He was the superintendent of schools in St. Louis just before the Civil War erupted.
Appointed Colonel of the 3rd Missouri Volunteer Regiment, Sigel was present at the CampJackson affair in May, 1861, and then lead a column to southwest Missouri as part of the pincer movement designed to trap State Guard troops retreating from central Missouri. He commanded the union troops on July 5, 1861, in the first major land battle of the Civil War, at Carthage, Missouri. At Wilson’s Creek, August, 1861, his command performed poorly, contibuting to the union defeat. In March, 1862, he participated in the Battle of Pea Ridge, and he performed ably there.
Transferred to the eastern theatre in 1862, Sigel was involved in a number of campaigns, without distinguishing himself, and then lost, ignominously, the Battle of New Market, Virginia, in May, 1864. He resigned his commission in 1865, when relieved of field command.
Sigel was a resident of New York City when he died in 1902.