Andre Malraux wrote, "It was in Spain that we learned that we could be right and yet be beaten, that might did not always conquer might."
C. Day Lewis, later Poet Laureate of Britain, opened his poem The Nabara (about a Basque armed trawler sacrificing herself to save a convoy from the fascists):
Freedom is more than a word,
more than the base coinage
Of statesmen, the tyrant's dishonoured cheque, or the dreamer's
Inflated currency. She is mortal, we know, and made
In the image of simple men
who have no taste for carnage
But sooner kill and are killed than see that image betrayed.
(Apparently, John McCain told an interviewer that his favorite fictional character is Robert Jordan, hero of Hemingway's For Whom the Bell Tolls. Which is interesting, as it is widely believed that the inspiration for that character was an officer in the Abraham Lincoln Battalion, a unit most of whose members were Communists.)