The war secrets were gathered by wives. Husbands were often stupid enough to believe they could say anything around their wives. Believing their wives were inept. They weren't.
Secrets were sewn into the women's hats and transported that way. Peggy was good. She was polished enough; from years of finishing school, that most men ignored her. Not quite as pretty as her older sister so she was often forgotten. This worked to her advantage.
Her brother in-law Hamilton wasn't even aware of her war involvement. She was good. Hercules Mulligan was impressed.
And Peggy? Well, she was a spy.