The JM Chapman was a 90 ton schooner. She was purchased by Asbury Harpending in 1863. Harpending was a member of the Knights of the Golden Circle in San Francisco, California. Harpending’s plan for the Chapman was to raid ships belonging to the Pacific Mail Steamship Company carrying gold and silver to Panama. Then Harpending would send prizes back east to be used to support the Confederacy.
Harpending's plans were detected and on March 15th 1863 the Chapman was boarded by sailors of the USS Cyane. The 15 man Confederate crew of the Chapman was placed under arrest by the San Francisco police. Those men were held at Alcatraz until after the end of the Civil War.