Officer Ditzy "Derpy" Doo was an academy student just as the First Great War started. She had tried so hard to accomplish her dream of being an officer of the law, and hated the thought of giving that up for the draft. However, her superiors thought she ought to finsih her training and stay stateside in order to keep the civilians safe during invasion.

She was given her badge and stationed in Las Pegasus, where she had to simultaneously fight the already present crime wave as well as the few odd enemy soldiers who slipped past Equestrian forces.

She sustained a few gun shot wounds, but nothing fatal. She and her husband managed throughout the war, ambling by, while awaiting Dinky Doo's return.

Long after the war ended she remained with the Equestrian Police Force, eventually making Captain of the PPD (Ponyville Police Department).

By the way, here eyes aren't constantly like that. She sought therapy and medical treatment after she had Dinky and was able to fix them. They will default to wall-eyed and she will occasionally wear an eyepatch to assist her in concentrating, but she can see perfectly fine.