The offer by the Navy Department of one regiment of Marines to be reorganized as Infantry was accepted by the Secretary of War, and it became temporarily a part of the First Division.
On June 14, 1917, the first expedition of American troops left the United States for France and the Fifth Regiment of Marines embarked on the naval transports Henderson and Hancock, and the auxiliary cruiser De Kalb (former Prinz Eitel Friedrich), formed approximately one-fifth of it. The fourth group, including the Hancock, did not sail until June 17, 1917.
The orders received by the convoy commander on the day prior to sailing read in part: “A military expedition is to be embarked on the above-named transports, augmented by a regiment of Marines embarked in naval vessels, for transportation to a destination already communicated.”
The De Kalb was in group 1, the Henderson in group 2, and the Hancock in group 4; all were part of the escort and not the convoy.
Rear Admiral Albert Gleaves, the convoy commander, flying his flag on the Seattle, personally commanded the first group, while Maj. Gen. W. L. Sibert in the Tenedores, was the senior Army officer embarked.
The passage of the four groups across the Atlantic was successfully accomplished without a single disaster, or the loss of a life due to enemy causes.
At 10.15 p. m., June 22, 1917, the first group, including the De Kalb, was attacked by enemy submarines. The wake of a submarine was sighted crossing 50 yards ahead of the Seattle’s bow from starboard to port. A few seconds later the De Kalb and Havana sighted torpedoes and opened fire. Two torpedoes passed close to the Havana, and one passed ahead and one astern of the De Kalb. The second group encountered two submarines, the first at 11.50 a. m., June 26, 1918, about 100 miles off the French coast and the second two hours later.
The De Kalb arrived at St. Nazaire, France, on June 26, 1917, the Henderson on June 27, 1917, and the Hancock on July 2, 1917. On June 27, 1917, the commanding officer of the Fifth Regiment reported to the commanding general, First Division, American Expeditionary Forces, and from that date the Fifth Regiment was considered as being detached for service with the Army by direction of the President.
Five hundred negro stevedores had been brought from the United States by the Army to discharge ships, but they were found inadequate for the large number of ships concerned. The Marines relieved the situation somewhat by turning to and discharging their own vessels.