The regiments of the United States Marine Corps began to swell in the early March of 1917, shortly after the Kaiser launched his campaign of unrestricted submarine warfare. When Congress declared war the following April, the expansion began is earnest:
"The Act of Congress making naval appropriations for the present fiscal year carries a proviso increasing the Marine Corps from its permanent legal enlisted strength of seventeen thousand and four hundred to a temporary war strength of seventy-five thousand and five hundred with a proportional increase in commissioned and warrant officers and the addition of two major generals and six brigadier generals."
Click here to read about the first Black Marines.
Read what the editors of YANK MAGAZINE thought about the Marine Corps Magazine, LEATHERNECK...