The two women sitting on their duffel bags in the D.C. Armory yesterday morning had thought that today would be the start of a long holiday season with their families.

But their D.C. Army National Guard Unit, the 115th Mobile Army Surgical Hospital, was activated last week as part of Operation Desert Shield.

Instead of planning family dinners, they were scrambling to prepare to leave their families for destinations unknown.

"It's going to be kind of sad," said Capt. Shade, whose civilian job is working as a nurse at Washington Hospital Center.

"Kind of sad?" asked Shade's partner-in-waiting, Maj. Woodson, a psychiatrist. "Try very sad."

The 115th MASH is the second unit of the D.C. Army National Guard to be activated as part of Operation Desert Shield.

The seriousness of the deployment hit unit members as soon as they arrived at the Armory. Officers told them not to reveal their full names to reporters as a security measure for their families.

Several hundred doctors, nurses and support staff members -- all of whom live within 50 miles of the District -- reported to the D.C. Armory yesterday for briefings and inspection of their personal gear.

Some went to Bolling Air Force Base to begin loading equipment ranging from bandages to surgical tools into the fortified mobile buildings that will serve as operating rooms once the unit reaches its destination.

Exactly what that destination will be, no one in the unit knows for sure. Not yet, anyway.

The unit's mission is to provide emergency surgery and medical treatment. But that doesn't mean the group will definitely head for the Middle East.

"That decision is up to the active Army," said Harry M. Dorsey, a spokesman for the commanding general of the D.C. National Guard.

Shade has two sons in college. This holiday season will be the first she will not be with them.

"When you sign up with the Guard, you know something like this is possible," Shade said. "But to actually have to deal with it is something else."

While many talked of sadness and fear, at least one expressed excitement.

"This is what we've been trained for," said Capt. Miller, who works for the Close-Up Foundation, which brings high school students to Washington for seminars with bureaucrats and elected officials. "I'm excited and eager to go."

Miller said she will lose a lot of money, possibly half of her income.

"But again, that's okay. My father was a captain too. He served in World War II. It's time for me to do my part. If anything happens, I've lived a good life."

The transition from civilian to military life is even more difficult when it comes on a holiday eve.

"The fact that it falls the day before a holiday, the day of a holiday or the day after a holiday is unfortunate," Dorsey said. "But we're responsive to the mission, and we have a larger goal.

"We're giving them half a day off . . . to celebrate Thanksgiving with their families."

The unit will return to the D.C. Armory tomorrow. Saturday morning, it will hold a farewell ceremony before moving to Fort Belvoir, where the group will learn its destination.

Unit members with young children said they had spent the last several days trying to explain what the possibility of war means and to reassure the children that their parents would be home again.

The task was not easy, many of them said, because they lacked information about where they were going or for how long.

Cpl. Thomas, a communications equipment operator, said his 12-year-old son and 11-year-old daughter "just don't understand."

"This is the first time I'll be away from them for the holidays," Thomas said. "I just tell them that I'll be back."

Woodson, the psychiatrist, discovered that she won't be shipping out at all. Her husband, a nurse, is also a member of the 115th MASH unit. Only one member of a family can be called up for active duty, they were told.

"We flipped a coin," Woodson said. "He lost."