Complex sentence: In 1917 when Loretta Walsh became the first women to enlist; but it was not until 1948 that a law was finally passed that permanently made women a permanent part of the military services.
Split into simpler sentences: In 1917 when Loretta Walsh became the first women to enlist. But it was not until 1948 that a law was finally passed that permanently made women a permanent part of the military services.