Heinlein on Preventing WWIII

Heinlein wrote Forrest Ackerman offering condolences on the loss of his brother, KIA in the Battle of the Bulge. Most of it is explaining why RAH didn't want to contribute to a memorial fanzine, on the grounds that he was angry at fans collective failure to support the war effort. Of most interest to me was a bit at the end:

The second job is, now and after the war, to see to it that it shall not happen again. There are many ways to do that and each must select his own---political activity of every sort, writing intended to stir people up, the willingness to combat race hatred, discrimination, limitations of civil liberty, generalized hates of every sort, whenever and wherever they show up. But I am damn well sure that fan activity is not the way to serve Alden's memory. Fandom has had a chance to prove itself and it has failed.