British Citizen

Before the French revolution it was common for officers to serve in foreign armies and even in several different armies during their careers. Even after the French Revolutionary and Napoleonic Wars it was still common to have foreign officers in various armies.

Here are a few foreign born US officers of the era that I could remember.

John Basil Turchin, brigadier general of US Volunteers in the Civil War, was born Ivan Vassilyevich Turchaninov in Russia.

Franz Sigel (1824-1902) was German born, a Lt. in the Baden army, a colonel in the revolutionary forces of Baden, and a Major General of US Volunteers and corps commander in the Civil War. Sigel commanded the Union forces at the Battle of New Market in 1864.

At the Little Bighorn foreign officers of the 7th cavalry included:

Lt. Charles Camillo DeRudio (1832-1910), commander of Company E, an Italian who had narrowly escaped execution for trying to assassinate Napoleon III.

Captain Myles Keogh, commander of Company I, killed in Custer's last stand, an Irish born (thus born a British subject) veteran of the Papal army.

The Canadian born (and thus born a British subject) Lt. Donald McIntosh (1838-1876), Commander of Company G, killed in Reno's valley fight, was the most exotic, since he was half or three quarters Indian. His mother was said to be descended from Red Jacket (c.1750-1830). His brother Archie married an Apache woman and some of their Apache descendants were named Donald McIntosh.

Philippe Régis Denis de Keredern de Trobriand (1816-1897) was a french aristocrat who became brigadier general of US Volunteers during the Civil War. After the war he became a colonel in the regular army and commanded several forts such as Fort Stevenson, Dakota 1867-69, Fort Shaw in Montana, and Fort Steele in Wyoming. So he is an example of a French born officer in command of several forts and military units in the US west.

Patrick Edward Connor (1820-91) was born in Ireland and thus was born a British subject. He became a brigadier general of US Volunteers during the Civil War, commanding in Utah and later in the District of the Plains containing Utah, Colorado, Nebraska, and Idaho territories. He commanded in the Battle or Massacre of Bear River, January 29, 1863, and in 1865 commanded the Powder River Expedition with 2,600 men in three columns against the Sioux, Cheyenne, and Arapaho. So he certainly counts.