WASHINGTON (AP) _ The United States, Britain, Canada and Australia will stage a special ''command post exercise'' next month at Fort Ord, Calif., the Pentagon said Friday.

The exercise, code-named Caltrop Tyro, will bring together about 600 soldiers from Britain's 24th Infantry Brigade, Canada's 1st Canadian Brigade Group, Australia's 6th Infantry Brigade and the U.S. 7th Light Infantry Division.

The exercise will involve the use of a ''computer-assisted battle simulation system'' to test the ability of staff officers from the four armies to work together in an allied command post, directing mock armies.

The exercise is scheduled to run from Nov. 15-18, although some advance teams will arrive in California shortly, the Pentagon said.