First alerted by shore-based radar "eyes", the escort screen went to general quarters at 1316 on 11 May, beginning the first of five successive "on again—off again" alerts. "Walter S. Brown" took station on the starboard bow of the convoy, some from the guide. In "Campbell", the commander of the screen, Jesse Clyburn Sowell, enjoined his escorts to be especially vigilant and warned that a dusk attack was well within the realm of possibility. At 2025, radar noted the approach of enemy aircraft; and Sowell formed his charges into eight columns apart to allow for plenty of maneuvering room. As UGS-40 went to general quarters at 2043 that evening, and took stations on "Walter S. Brown's" flanks.