Complex sentence: He protested this appointment because he feared he would remain there for years, sidelined as World War II loomed, but he only remained in this station for three months after an organizational shift in the Bureau of Aeronautics.
Split into simpler sentences: He protested this appointment because he feared he would remain there for years, sidelined as World War II loomed. In the event he only remained in this station for three months, following an organizational shift in the Bureau of Aeronautics.