The collected short story to novella length works by H. Beam Piper that are not part of his "Terro-human" future history.

Time and Time Again - After a blast in a nuclear war, Alan Hartley wakes up thirty years earlier in his own 13-year-old body. He sets out to make his father President so as to avoid the terrible wars which devastated his previous future.
The Mercenaries - A team of Free Scientists working for the Philadelphia Project (the Western Union's moon project) is threatened by a traitor.
The Answer - Research into "negamatter" leads to a startling discovery about the start of a nuclear war that happened fifteen years earlier.
Hunter Patrol - Many men have dreamed of world peace, but none have been able to achieve it. If one man did have that power, could mankind afford to pay the price?
Crossroads of Destiny - A discussion about a TV show which shows how events in history might have happened differently is joined by a man who is actually from an alternate reality.
Day of the Moron - It's natural to trust the unproven word of the fellow who's "on my side" - but the emotional moron is on no one's side, not even his own. Once, such an emotional moron could, at worst, hurt a few. But with the mighty, leashed forces Man employs now.
The Return - The isolated little group they found were doing fine - but their religion was most strange - and yet quite logical!
Dearest - A powerful short story about an old soldier, greed and a mysterious being.
Flight from Tomorrow - At the last moment of his overthrow, a ruthless dictator steals the only time machine and goes back to ancient (our) times to establish a new empire. But he brought with him more than just bad habits.
Operation R.S.V.P. - Bombs, guided missiles, bacteria: none is as deadly as a glib-tongued diplomat.