According to the official record in the National Archives, U-boat activity in Maine waters was limited. Most occurred near Mount Desert Rock, about 30 miles southeast of Mount Desert Island. There, between 1942 and 1944, German submarines sank two freighters and attacked a fishing boat. More than 100 seamen were killed. Navy investigators blamed the crash on pilot error.
Most historians agree that the official record of U-boat activity off Maine is incomplete.
Duncan recalls a time in 1942 when a patrol plane's crew saw a U-boat on the surface about five miles southeast of the Portland Sea Buoy. A destroyer was rushed to the scene. Its crew dropped depth charges and later saw an oil slick. The Navy sent the destroyer McCalla from Portland. Oil came to the surface, and the next day, bodies of German sailors washed ashore on Small Point.