Tso Tsung-t'ang (alternately Zuo Zongtang) was a Chinese general during the late Qing dynasty, most famous for helping to quell the Taiping rebellion.

I'm about to commit a horrible sin for /r/AskHistorians by linking to a TED talk. Nevertheless, this talk by Jennifer 8. Lee (coincidentally titled "Who was General Tso?") is actually rather informative on the subject of American "Chinese" cuisine.

To answer the sub-question, "General Tso's chicken" is an entirely American invention.