By coincidence I was reading a copy of Short Wave Magazine from 1939 - the last edition before WWII.  It gives the result of a QRP competition (OK, "test").  It's the most delightful of articles embodying more than 80 years ago the spirit of Hans's QCX challenge.  One thing I really like is that the transmitter power was defined as whatever the operator chose to make from a "standard 120V dry HT battery".  The highest (input) power was 3.5W, the winner used 1.8W.  Which bands?  40 and 20 of course.  

I think it's well worth a read - I've uploaded a copy of the magazine - as SWM-1939-09.pdf you'll find the article at page 27.  So much changes, so much it's the same thing.