[2] In 1907, President Roosevelt appointed Army Lt. Col. George W. Goethals to the post of Chief Engineer of the ICC, officially turning construction of the Canal into a military project.

They would form the nucleus of a mobile force that grew to include other infantry, cavalry, engineer, signal, and field artillery units, as well as a Marine battalion that had protected the Canal since 1904.

The department was also responsible for the laying, maintaining, and clearing of harbor defense minefields that were to be placed at the canal entrance in event of a war.

Four infantry and one engineer regiment, plus two artillery battalions were assigned to the Mobile Force, even after World War II began.

The Atlantic side was considered the least likely invasion route because the few landing areas there were too small to allow the discharge of numerous forces simultaneously.