Short answers, pulled from the story.
Franz Sigel was a German-born Union major general during the American Civil War, born on the 18th of November 1824 in Sinsheim, Baden. He was significant primarily for his ability to recruit German-speaking immigrants to the Union cause, a role that received the direct approval of President Abraham Lincoln despite Sigel's mixed military record.
Sigel led the revolutionary forces in Baden as colonel, and in April 1848 he organized the Sigel-Zug, a militia of more than four thousand volunteers for a siege against Freiburg. His militia was defeated on the 23rd of April 1848 by numerically inferior but better-led troops. By 1849, he had become Secretary of War and commander-in-chief of the revolutionary republican government of Baden.
Sigel's finest battlefield performance came at the Battle of Pea Ridge on the 8th and the 9th of March 1862 in Arkansas. On the 9th of March, he personally directed the Union artillery attack that routed the Confederate forces under Major General Earl Van Dorn.
The reasons were disputed: some accounts cited failing health, others that Sigel protested the small size of his corps and asked to be relieved, and many historians point to his lack of military skill and multiple decisions that resulted in unnecessary soldier deaths. General-in-Chief Henry W. Halleck, who detested Sigel, worked to keep him on light duty after the relief.
Sigel was soundly defeated on the 15th of May 1864 by Major General John C. Breckinridge. The defeat was particularly embarrassing because of the prominent role played by young cadets from the Virginia Military Institute. Sigel was replaced by Major General David Hunter following the battle.
Sigel died in New York in 1902 and is buried at Woodlawn Cemetery in the Bronx. Statues of him stand in Riverside Park at the corner of 106th Street in Manhattan and in Forest Park in St. Louis, Missouri. Streets, a park in the Bronx, the village of Sigel in Pennsylvania, and Sigel Township in Minnesota were also named after him.