National Defense Act of 1916

166, enacted June 3, 1916, was a United States federal law that updated the Militia Act of 1903, which related to the organization of the military, particularly the National Guard.

The Army began the creation of an Aviation arm, and the federal government took steps to ensure the immediate availability of wartime weapons and equipment by contracting in advance for production of gunpowder and other material.

The act was passed amidst the "preparedness controversy", after Pancho Villa's cross-border raid on Columbus, New Mexico and prior to U.S. entry into World War I.

[2] Sponsored by the committee's ranking member, Julius Kahn of California and drafted by Hay, the 1916 law authorized an expanded Army of 175,000, and an enlarged National Guard of 450,000.

Present to testify as an advocate of a Reserve Engineers Corps, he expanded his remarks to argue in favor of the "Ohio Plan".

[11] In addition, the Army was prevented from recruiting volunteer units to expand the organization in time of war until after the National Guard had been called up.

[17] As part of the debate over preparedness, Congress was concerned with ensuring the supply of nitrates (used to make munitions), so the 1916 Act authorized the construction of two nitrate-manufacturing plants, an industrial village, and a dam to provide them hydropower.

This enhanced the 1916 Act's mobilization provisions, making it possible to deploy National Guard units and individual members directly for overseas service in the event of a war.