When Melvin Cammon reported for active duty with his fellow D.C. National Guard members two weeks ago, he was the only one who did not spend the night with the unit.

A few hours after reporting, Cammon got a call from his wife, Carol, who had just gone into labor with the couple's first child. Cammon's commander provided an Army car and a driver, who took him from the D.C. Armory to Holy Cross Hospital to be with his wife.

Yesterday at Fort Meade, Cammon, a Forestville industrial worker, celebrated his daughter's two-week birthday with his wife and his mother, Claraetta. Everyone knew it might be a year before the family can be together again. By that time, Cammon said, his daughter, Candus, would be walking and maybe talking.

Cammon's bittersweet celebration was one of hundreds yesterday when about 400 members of three D.C. guard units got a last chance to be with their families and friends during the units' family day at Fort Meade, a traditional picnic held just before a unit is deployed. None of the guard members knows when they will depart for Saudi Arabia.

Three District military police units, which have trained at Fort Meade, and a fourth that has trained at Fort A.P. Hill in Virginia could be deployed to Saudi Arabia as soon as this week.

The units will be part of a vast support group based in the rear of what could be a long front line along Saudi Arabia's border with Kuwait and Iraq. The military police units will have the job of guarding and transporting Iraqi prisoners of war, escorting convoys of troops and supplies and possibly filling in as infantrymen.

For the last two weeks, said the brigade commander, Brig. Gen. Stanley J. Haransky, the units have been "fine-tuning the skills they already have," including the donning of chemical gas masks in the required nine seconds.

Haransky, who runs a catering service in civilian life, will stay in Washington. But, he said "it's very conceivable" that he could be deployed with other units under his command if the war produces a large number of Iraqi prisoners.

Haransky said he had gotten lots of questions from mothers, wives and husbands of unit members about the length of their tour in the Persian Gulf. He said he told everyone to expect the tour to be up to a year.

Virtually no one in the units has questioned what some have said is a disproportionately large call-up of District guard members, Haransky said. According to figures provided by the Pentagon, more members of the D.C. National Guard have been activated per capita than from all states except Louisiana, Mississippi and Wyoming.

"We're basically military police, and you have a high concentration of that on the East Coast," Haransky said. "We expect to be called . . . a number of our units were deployed to St. Croix after Hurricane Hugo and to Panama."

Haransky said he thinks the units "are absolutely, positively ready to go." But a brother of one of the soldiers in the group was not so sure.

Marlon Curtis, 38, a Vietnam veteran, said "there is a world of difference" between the training he received as a member of the Army's 101st Airborne and the training his brother, Timothy, has had in the guard.

Sgt. Timothy Curtis, 35, a Hyattsville cleaning firm manager, agreed. "We have had excellent training, but it's not like being in the active Army."

The family also is seeing a brother-in-law off to Saudi Arabia. Sgt. Alton Butler, 42, also a Vietnam veteran, said there may be problems ahead for his fellow guardsmen who have never faced combat.

"As for me, it's been 23 years, so I know I'll have some adjustments to make," Butler said. Another brother-in-law already is serving in Saudi Arabia.

Virtually no one at the guard celebration openly criticized the war, but there was little sign of enthusiasm for the guard's deployment.

Marlon Curtis said he believes many people have had an unpleasant sense of foreboding, particularly those like his brother-in-law who have seen combat before.

"You get this feeling in the back of your head," he said. "Maybe this is one war too many."