West Tisbury School principal Michael A. Halt, a lieutenant colonel in the United States Marine Corps Reserves, was called back to active duty this week and will leave for training in just over a week to prepare for a tour of duty in Iraq.

Mr. Halt received the official letter on Wednesday and has known with near certainty that he would be leaving for a little more than two weeks. He must report for duty by Jan. 15.

A military advisor to United States Navy Seabees - the construction battalions of the Navy - the 42-year-old Vineyard Haven resident will train a unit of nearly 200 men in Port Hueneme, Calif., for six to seven months before going to Iraq for seven to eight months. There, his unit, the 7th Naval Construction Regiment, will do "everything from building schoolhouses for kids to repairing roads that have been damaged by the insurgents," Mr. Halt said.

"I'm their military advisor," Mr. Halt explained yesterday. "I'm paid to make sure the 196 guys I leave California with all get back in one piece. I make sure they are tactically and technically proficient in the art of war."

The military has told him to anticipate being away for 12 to 24 months.

"It saddens me to tell you that Friday, Jan. 12, 2007 will be my last day at work at the West Tisbury School until I am released from active duty following the completion of my tour of duty in Iraq," Mr. Halt wrote in a letter sent home with students this week. "I will be informing the students of my absence in an age-appropriate manner in the next two days. Additionally, I will be working closely with Dr. Weiss, the superintendent of schools, to help ensure a smooth transition with my interim replacement," he added.

Vineyard schools superintendent Dr. James H. Weiss said the outlook is good on finding an interim principal to work alongside assistant principal Robert C. Lane. He has been in communication with potential candidates, including four retired school administrators living on the Island.

"I hope to be able to name somebody on Monday," Mr. Weiss said. "My main concern right now is with Michael and his family. These are trying times and I want him to be safe and return to us and continue being principal of the West Tisbury School."

Mr. Halt's wife Laurie Halt teaches history at the Martha's Vineyard Regional High School. His children, Cooper, 17, and Connor, 16, attend the regional high school and his 13-year-old daughter Maggie attends the Tisbury School.

The news of Mr. Halt's departure comes at a time when the superintendent is also finding a new principal for the Edgartown School; principal G. Paul Dulac resigned last month.

"This is a little more difficult," Mr. Weiss said. "In this case, it's an indeterminate sentence. He could be gone six months, 12 months - anywhere up to 24 months." Mr. Halt and Mr. Weiss spoke with the school staff about the upcoming transition on Wednesday and plan to meet with the up-Island regional school district committee to discuss leadership plans.

Mr. Halt is a veteran of the first Gulf War. He joined the Marines in 1987 after college and served five years on active duty before pursuing his passion for teaching. In 1997, he came to the Vineyard to teach history at the regional high school and held that position for three years before becoming assistant principal of the school in 2000. He became principal of the West Tisbury School in 2004.

Mr. Halt received a warning order from his unit before Thanksgiving and he informed Mr. Weiss privately that there was a possibility he would be called away. Like Mr. Halt, this was not the first time Mr. Weiss contemplated what he would do in this situation.

"In the last several months, I've certainly been thinking about it," Mr. Weiss said.

This is the second time Mr. Halt has been called away for active duty since he joined the Marine Corps Reserve in 1992. After the attacks of Sept. 11, 2001, while he was an assistant principal, Mr. Halt trained Seabees in North Carolina for 13 months. Since Sept. 11, the chance of being called into active duty has remained high.

"It became a reality that everyone was painfully aware of," Mr. Halt said. "You don't want to live every day like you're leaving tomorrow, but you do want to make sure that if you're called away, you and your family are ready for it."

Mr. Halt said he keeps all of his military things in one place and tries to stay organized at work in the event he is called away. When it comes time to pack, it won't take him more than 20 minutes, he said - less time than it will take him to clear off his desk at work.

"When I got out of the Marine Corps I suddenly realized I missed it and I joined the Marine Corps Reserves," Mr. Halt reflected. "I'm looking forward to returning to my family, but there is a camaraderie and a sense of purpose you have when you're on active duty in the military that you do not find anywhere else in the world and I'd be lying if I said I didn't enjoy both those things. I look forward to spending time with my brothers in arms and I look forward to coming home as well."