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History and Heritage

The Navy in the Great War: The U.S. Joins World War I

A time of technological innovation

Throughout World War I, then known as the Great War, German U-boats stalked the U.S. coastline, playing cat-and-mouse with passenger and merchant ships that crossed the Atlantic to supply the Allies.

One of the most infamous incidents was the Lusitania, which was torpedoed off the coast of Ireland, May, 7, 1915. Out of more than 1,900 passengers, almost 1,200 were killed, including more than 120 Americans.

In Europe, the British and German fleets had fought each other to a stalemate in the Battle of Jutland, destroying about 25 ships, while on land, a generation of young men slaughtered and gassed each other in some of the most horrific fighting the world had ever seen.

The U.S. was officially neutral, and, in fact, much of the public was vehemently opposed to joining the war, according to Dr. Dennis M. Conrad of Navy History and Heritage Command.

Then, Germany avowed unrestricted submarine warfare against all ships in a restricted zone off the British Isles and France, Jan. 31, 1917, thereby putting "aside all restraints of law or of humanity," as President Woodrow Wilson said. U-boats went onto sink a number of American merchant ships over the next few months.
Two photo collage: U.S. Navy fleet in Virginia WWI; U.S. Navy submarine at sea


Germany also invited Mexico to invade the U.S.

The military set about preparing for war. In fact, the Navy would grow from 58,527 Sailors and officers in mid-1916 to 497,030 men and women by the day of the armistice, Nov. 11, 1918.

The U.S. broke off diplomatic relations in February, and "it's a quick downhill from there until the declaration of war on April 6," Conrad said. Congress passed the bill late that morning, and rushed it to the White House for Wilson's signature.

"He's at lunch," Conrad said. "They rush in with this war proclamation, Wilson borrows a pen from his wife, signs it.

The usher pushes a button and in Wilson's executive office is his naval attache. ... He rushes up to the roof of the White House, gets some flags, starts signaling - in those days, the Navy Department was in the Old Executive Office Building, which was across the street. - Dr. Dennis M. Conrad


He wig-wags over to the Navy office building and they shoot out telegrams to all the naval commands saying, 'We're at war. Be careful. The Germans may attack you. Be ready.'"

Flags announcing the start of the war went up minutes later on the flagship USS Pennsylvania (BB-38), then moored with most of the Atlantic Fleet on the York River in Virginia, behind a metal net that protected the ships from submarine attacks.

World War I, Conrad continued, would primarily be a land war for the United States, but the Navy performed a number of critical functions, especially escorting merchant ships, which carried food and other vital supplies to the British, who the Axis powers were attempting to starve into submission. The Navy also safely transported Soldiers across the Atlantic. This was crucial, he said, because German war plans included sinking those troop ships before the American Expeditionary Force could make it to France, causing untold loss of life and crushing American morale.

By that definition, he said, the Navy won World War I.
Three photo collage: USS Minnesota at sea; Sailors aboard Navy ship; Navy ship firing weapons


"Our naval forces have operated in European waters from the Mediterranean to the White Sea," Secretary of the Navy Josephus Daniels reported in November 1918, noting almost 2,000 ships and submarines supported the war effort. "At Corfu, Gibraltar, along the French Bay of Biscay ports, at the English Channel ports, on the Irish Coast, in the North Sea, at Murmansk and Archangel (Russia) our naval forces have been stationed and have done creditable work."

Some Navy men saw direct combat with the enemy; female yeomen took over important support duties at home; other Sailors manned lighthouses and guarded America's coasts; doctors, nurses and corpsmen saved lives aboard hospital ships; and still others took to the skies, pioneers in the infant field of aviation.

In fact, Conrad said, one of the most important aspects of World War I was the development of new technology, new weapons, new ways of waging war. World War I saw the beginning of aviation and the first aircraft carriers. It saw submarines and destroyers come to the forefront of naval warfare. It even saw the invention of depth charges and the development of sonar.

Really, it's a time of technological innovation," Conrad said, "but those changes don't come to fruition until ... the decades of the 20s and 30s." - Dr. Dennis M. Conrad


"They're invented then, but until they're perfected, it's really almost up to the eve of World War II."

Editor's Note: Stay tuned for future articles on the Navy and World War I.

To learn more about U.S. Navy History visit Navy History and Heritage Command.

Read about women in World War I here.

Navy Photo


Navy Photo