In which year did Opha Mae Johnson become the first female Marine?

Opha Mae Johnson became the first female Marine in 1918. This landmark event occurred during World War I, a time when the United States Marine Corps sought to expand its ranks to support wartime efforts. Johnson's enlistment marked the beginning of women's formal integration into the Marine Corps, a pivotal moment that opened the door for future generations of women to serve in various capacities within the military.

As the first woman to enlist, her involvement set a precedent that would lead to significant changes in the role of women in the military, allowing them to take on more diverse and critical roles over the years. The significance of her enlistment is recognized in Marine Corps history and culture, emphasizing the evolving nature of military service.

Considering the other years provided, 1910 and 1915 predate Johnson’s enlistment and do not align with historical records, while 1942 represents another era during World War II when women served in increased numbers but does not accurately reflect Johnson's groundbreaking achievement. Thus, 1918 is the correct year that marks the beginning of women's participation in the Marine Corps with Opha Mae Johnson's enlistment.