Many Americans began preparing for the entry into the First World War prior to the country's formal engagement in hostilities, notably in the formation of hospitals under the auspices of the Red Cross.

The university had begun making its own plans, and a compromise was reached where the medical school as a whole would form a unity, not just the Brigham alone.

[2] Col. Jacob Peabody of the local Red Cross chapter began a campaign to raise the $25,000 ($ 700,000 in 2025) worth of equipment required for a 500-bed hospital.

The Committee organized dressings which were then sterilized and packed into sealed tins to be distributed in France through the American Clearing House.

[5] Base Hospital No.5 was organized in February 1916 and mobilized in May 1917, stopping at Fort Totten, before boarding the RMS Saxonia for Falmouth, England.

At this time, there was no convoy in place, and while they did not encounter any enemy submarines they sailed through wreckage and remained on high alert until their arrival in England.

[9] Beyond the physical state of the site, the American forces found themselves underequipped and understaffed for a hospital of this size.

Though they requested more additional support from the War Department, it took six months to be filled and only a fraction of the personnel were granted due to other needs elsewhere.

[10] The drainage and vermin were not the only hazards of the site, located next to cement works and not far from a munitions dump, the area was under regular threat from German bombers.

Lt. Rae Whidden was injured and invalided home, but ultimately died of pneumonia following influenza later in the month.

Aubrey McLeod, Nurse Eva Parmelee, Lt. Thaddeus Smith, and twenty-two patients were seriously wounded in the attack.

[2] In this location, so close to England, they provided temporary care, food, and beds for those waiting to be transported home, as well as their usual duties.

On 22 December 1917, bombers hit the medical stores, the base's bakery and other sites, killing 52 people and wounding 172.

[14] This constant threat added to the great relief felt by the personnel when leave was granted after nine months of work.

From them until the end of the war, they saw a heavy succession of casualties from those of the 27th and 30th Infantry Divisions fighting at Kemmelberg and Messines Ridge on the Hindenburg Line with the British, and from the 37th and 91st serving with the French in Belgium.

[12][4] Even after the armistice was declared, sick and wounded continued to arrive from forward hospitals through November and December.