Ken Magazine stated in its first issue a disclaimer (actually written by Hem) "Ernest Hemingway has been in Spain since KEN was first projected. Although contracted and announced as an editor he has taken no part in the editing of the magazine nor in the formation of its policies. If he sees eye to eye with us on KEN we would like to have him as an editor. If not, he will remain as a contributor until he is fired or quits." Hemingway stayed on and contributed 14 articles and stories between April 4th, 1938 and Jan 12th, 1939. Notable stories include 'Dying, Well or Badly", Treachery in Aragon", "My Pal the Gorilla Gargantua" and the short story 'The Old Man at the Bridge".
These are scarce appearances of Hemingway, during his 'non-fiction' time in Spain during the Spanish Civil War. Since Hemingway was on the side of the Loyalists / Republicans, he was reporting on the atrocities committed by Facists / Nationalists (even though both sides committed these horrible atrocities). Much of the idea and body from For Whom the Bell Tolls was composed at this time, even though he would write it a few years later.
