During World War II Fieser was partly responsible for a military experiment that went disastrously awry. Project X-ray was a scheme to drop a great number of bats with small incendiary charges with a timed fuse attached over Japan to start widespread fires. After the bats nested in housing and factories, the timed fuses would ignite the incendiary charges (napalm) and start the fires. During a test run, a number of the bats escaped and ignited Carlsbad Airfield 's hangars, barracks, and a general's car. "The accidental incineration of Carlsbad Auxiliary Army Airfield by incendiary bats was both a high and a low for Project X-Ray."  Fieser omitted the account of the fires from his own account of the bat tests.