On May 6, 1937, the German zeppelin Hindenberg exploded while attempting to moor in Lakehurst, New Jersey, killing 36 people. The disaster resulted in the death of the commercial trans-Atlantic zeppelin service and the rise of the mass news media. On this date, still photographers, filmmakers, and radio broadcasters put together a perfect storm of coverage that set the stage for the future of communications.
At least it seems that way to me, but I'm no historian. Yet I can't think of any event before the Hindenburg explosion that equaled it's multi-media coverage.
There are a couple of angles here that are interesting for photographers today.
(And lots of interesting trivia: According to this article, the Hindenburg was to have been filled with non-flammable helium; however, the United States owned all the world's helium and had placed an embargo against selling it to Nazi Germany. The Graf Zeppelin Company, which built the Hindenburg, turned to hydrogen as an lifting agent. Kapow!)