Harry E. Lockwood, 51, a lieutenant colonel in the D. C. National Guard, where he also held a civilian position as State Maintenance Officer, died of a respiratory ailment Friday at Alexandria Hospital.

A Washington native, Col. Lockwood graduated from Roosevelt High School and attended American University. He was a resident of Alexandria.

In 1948, he joined the D.C. National Guard. Except for a break in service of seven months, he remained with the Guard and was commander of the 104th Transportation Motor Transport Battalion at the time of his death.

Before becoming a full-time civilian employe of the Guard in 1966, Col. Lockwood was a branch manager for loan companies in this area for a number of years.

As the D. C. Guard's State Maintenance Officer, he was the principal advisor to the Guard's commanding general on maintenance of Army surface equipment and supervised activities of the Guard's organizational maintenance and combined support maintenance shops at Anacostia Naval Air Station.

During the Korean conflict, Col. Lockwood served on active duty with the 260th AAA Gun Battaliton. After his release from active duty in 1952, he held a number of command and staff positions in artillery, engineer, military police, ordnance and transportation units and was attached to Guard State Headquarters. He was promoted to lieutenant colonel in 1976.

Col. Lockwood's military decorations include the D. C. National Guard Medal for long and faithful service.

Surviviors include his wife, Patricia, of Alexandria; two stepsons, Kirk Lockwood of Romney, W. Va., and Todd L. Newmark of Burlington, W. Va.; his mother, Catherine Rose Lockwood, and a sister, Lois Ann Bernas, both of Silver Spring, and a granddaughter.