|During the Civil War [1861-1865], the Army imprisoned deserters, insubordinate soldiers, and Confederate sympathizers on the island. In 1868, the Army established a permanent military prison on Alcatraz.
Soldiers convicted of crimes in court-martials [the military version of civilian criminal trials] could be sentenced to imprisonment at Alcatraz. At first, inmates were housed in various structures that the Army converted for use as prisons. In 1909, the Army demolished much of the original fort, and started building a new prison there.