This is a great collection of action short stories by H. Beam Piper from "The Golden Age of Science Fiction". Featured here: "Flight From Tomorrow", "Genesis", "Ministry Of Disturbance", and "Crossroads Of Destiny".
Henry Beam Piper (March 23, 1904 – c. November 6, 1964) was an American science fiction writer. He wrote many short stories and several novels. He is best known for his extensive Terro-Human Future History series of stories and a shorter series of "Paratime" alternate history tales.