On July 21, 1918, New Englanders found themselves with World War I on their doorsteps in the form of a German U-boat attack off Cape Cod at its eastern-most point. The German raider, U-156, destroyed 45 vessels over the course of its life – five of them off Cape Cod that day.
The attack came between 10:30 and 11 a.m. on the tugboat Perth Amboy, which was pulling four barges from Gloucester to New York. One was loaded with stone, the others empty after having delivered their loads of coal. The German sub first fired torpedoes at the tugboat, but all missed. The torpedo passing by was the first the tugboat knew that there was a U-boat in the area.
The sub then began shelling. The first shot hit the wheelhouse of the tugboat, setting it on fire. Then the Germans turned to the barges, sinking three of them efficiently. The final barge proved a more difficult target. Though they shelled it for a half-hour, it still stayed afloat.
The attack subsided temporarily when two planes from the Chatham Naval Air Station arrived. Tourist eyewitnesses, astounded as the fighting played out just off shore at Nauset Beach, saw one plane swoop low and the airman toss a something at the sub, but it did not explode. Later, newspapers would report that the airmen were student pilots and they tossed sand bags at the boat because they had no live ammunition.
As the plane circled back around for another pass, the sub stopped firing on the tugboat and barge and trained its machine guns on the planes. Within minutes, the German vessel submerged out of sight. It was a surprising and dangerous move in the shallow waters, but the boat stayed out of view and the airmen, thinking the enemy had left, returned to Chatham.
The attack was not over, however. After the planes had departed, the U-boat again surfaced and resumed firing until it sank the final barge. With the barges taken care of, the U-boat crew resumed shelling the tugboat. Only when the tug was in flames from the bow to the stern did the U-156 finally submerge and leave the area.
Rescuers from the lifesaving station pulled the tugboat’s crew to shore. The crew members from the barges all made it safely to land, most picked up from life boats by merchant vessels in the area. In all, 41 people had to be rescued, including three women and five children. One member of the tugboat crew suffered serious injury to his hand, which was hit by a shell fragment.
Several shells from the U-boat reached the mainland, but did no damage. The German attacks on unarmed merchant vessels, and the practice of sinking them without affording the crews a chance to escape, was one of the major stated reasons why the U.S. entered the war in 1917. And the summer tourists got a first-hand look at exactly what that type of warfare looked like.
In part, U.S. intelligence said, the show was probably deliberate, designed to undermine American confidence as the natiion expanded its troop presence in Europe.