After another tour of duty in the Philippines, Marshall returned in 1916 to serve as aide-de-camp to the commander of the Western Department, former Army chief of staff Major General J. Franklin Bell, at the Presidio in San Francisco. After the United States declared war on Germany in April 1917, Marshall relocated with Bell to Governors Island, New York when Bell was reassigned as commander of the Department of the East. Shortly afterwards, Marshall was assigned to help oversee the mobilization of the 1st Division for service in France.