As the Great War raged on, the logistical challenges of transporting soldiers across the Atlantic to the frontlines in France were immense.

Navigating the treacherous waters, protecting against the ever-present threat of German U-boats, and efficiently moving thousands of troops and their supplies were paramount concerns for the Allied forces.

The primary mode of transatlantic transport was by ship, with the majority of American soldiers making the journey aboard large ocean liners that had been converted for military use.

These vessels, such as the RMS Leviathan and the USS Agamemnon, were capable of carrying thousands of troops at a time, along with their weapons, equipment, and provisions. - https://francefocusguide.com/blog/how-soldiers-traveled-to-france-in-ww1/

"The Transatlantic Journey: How WWI Soldiers Reached the European Front"