The mission of Camp Mills was initially the preparation of Army units prior to their deployment to Europe in World War I.

It was established as temporary tent camp in September 1917 as a place to mobilize the 42nd Division, made up of National Guard units from various states.

The camp was then ordered to be abandoned, but reestablished April 4, 1918, as a part of the New York Port of Embarkation at Hoboken, New Jersey to obtain additional facilities for troops in transit to Europe.

The units waited until they could be scheduled for embarkation whereupon they would travel by trains of the Long Island Rail Road (LIRR) to board ferryboats for the overseas piers in Brooklyn or Hoboken and loaded onto troop ships.

A very large number of American soldiers shipped out to France from Camp Mills, at its peak in September 1918, over 31,000 troops were stationed there.

Notable individuals who were assigned during World War I were: Douglas MacArthur, Wild Bill Donovan, Joyce Kilmer and Father Duffy among them.

With the end of World War I in November 1918, Camp Mills served as a demobilization center processing thousands of troops back into the United States.