Within hours of the strike against Pearl Harbor, the U.S. military sprang into action to implement a "contingency plan" previously drawn up to protect the coast against a full-scale German invasion or incursions by Nazi espionage agents and saboteurs. The War Department placed the 26th "Yankee" Division (YD) under the jurisdiction of the 1st Coast Artillery District, a subdivision of the U.S. Army Coast Artillery Corps. Military leaders charged the division with securing the coast of New England and Long Island, later expanding its area to include the entire eastern seaboard. Focusing primarily on the unit's work in "home defense" from January 1942 through November 1943, this history begins with prewar activation and training and recounts in detail the two highly publicized incidents of saboteurs coming ashore in June 1942. Also included are reports of U-boat sightings and encounters with subversive agents by veterans of the YD while on patrol. Firsthand accounts by members of the division provide a look at day-to-day operations. Appendices contain a number of previously unpublished historical documents. Many period photographs complete this history of a previously undocumented chapter of World War II history.