"Enemy" planes flying over Harvard yesterday afternoon shattered generations of tranquility in the pursuit of knowledge by dropping 120 high explosive and incendiary bombs, leaving Massachusetts Hall in wreckage, blowing up water and gas mains, and setting fire to President Conant's house.

The bombs, of course, were imaginary, but the whole incident was a test of the efficiency of Cambridge's air raid defense authorities, and partly also of Harvard's embryonic warden organization. The skies of Boston, clouded by yesterday afternoon's rain, were filled with United States air force planes in connection with the manoeuvers this week.

Complete emergency equipment, including special fire hose trucks, equipment for demolition squads, autos for first aid workers, and scores of city deputy wardens, were in readiness for the raid. Chief warden of the Harvard district was Aldrich Durant, business manager of the University.

Defense Organization Good

Questioned after the raid, which lasted from 2:30 to 2:50 o'clock, he expressed satisfaction with the speed and efficiency with which the Harvard forces went to the scene of the damage and discharged their duties. "If an actual raid had been in progress we would have had the situation well under control," he said, "but most of the real credit goes to the well-trained city defense organization.

First warning of the approach of the raiders was received at 12:30 o'clock, and emergency crews were called to be in readiness and to maintain contact with the Chief Warden's control post in the Yard.

Four city volunteer wardens were stationed in each of the University's buildings to await possible damage. These central emergency equipment posts with trucks, fire hoses, and tools, were stationed at Harvard Hall, in the maintenance building on the river, and theoretically in the Music building quad- rangle.

"Damago" reported by Durant's crew included 12 high explosive and incendiary bombs in the Yard, all in the open except for the one which hit Massachusetts Hall, caused four casualties and trapped six people in the wreckage. Fire started, but the truck and first aid squad stationed outside Harvard Hall put the fire in check