Strauss tried to enlist at the outbreak of war, but was rejected as under age. He did, however, serve the Confederate cause through his trading activities.
Edward Crosby served in the First Michigan Cavalry and was in action at Bull Run, Antietam and Gettysburg.
Frank Millet, aged only 15, assisted his surgeon father at a military hospital in Fredericksburg. At the age of 17 he enlisted as a drummer for the Union a few months before the war ended, but didn't see any active service.
Samuel Risien (3rd Class) served on Confederate ships during the Civil War.
Archibald Gracie's father was at the Battle of Chickamauga (Sept. 1863) as an infantry officer on the Confederate side, which inspired Gracie to write a book The Truth about Chickamauga and, after surviving Titanic, The Truth about the Titanic. I don't suppose you were interested in anyone whose ancestors served in the Civil War, but Gracie is worth mentioning if you don't already know of him.