The Old Mission is a location on Mars.
The Martians of Mars designate the Old Mission as Ummana’fe. During the second War of Two Worlds, the Martians who contracted Small Ox were sent to the Old Mission for convalescence. The youngling Croach the Tracker was one such Martian.
In the present day, the Old Mission is mostly a ruin. The only known inhabitant is the Space-Crazy Preacher. The Preacher buried land mines around the mission in order to kill any Martians who trespassed in the area.