On February 15, 1898, The USS Maine's forward 6" ammunition bunker exploded. 266 U.S. Navy sailors were killed.

The Press and the U.S. public were quick to blame Spain for the sinking. Spain vehemently denied any involvement. An initial investigation by the U.S. government determined the cause of the sinking to have been a high explosive mine from outside the ship. The U.S. government never accused Spain of sinking the Maine but 2 months after the sinking the US and Spain were at war. "Remember the Maine to hell with Spain" was a common rallying cry for the war.

In 1911 a second US government investigation also concluded that an external explosion caused the magazine to explode. This report though disagreed on the exact circumstances of the explosion believing it to have occurred much further back and to have had a lower yield.

In 1975 Admiral Hyman Rickover convinced the US Navy to conduct a third investigation although this one was unofficial. This investigation concluded that the most likely cause of the explosion was an internal fire in the coal storage which was located adjacent to the forward 6" ammunition storage.

In 1999 PBS conducted an investigation that agreed with the external explosion cause.

In addition to the physical evidence, however, I think a look at the political landscape is very telling. In 1898 the United States was the second or third largest industrial power in the world (very close to tied with Germany depending on how you read the figures) Spain was still largely agricultural with their industrial power about 1/30th that of the US. The US population was about 4 times that of Spain. Spain's colonies (Cuba, The Phillipines) were nearly in revolt. The USS Maine was one of 8 US battleships. Spain had only a single battleship (which could not carry enough coal to travel from Spain to Cuba without refueling). Spain was aware of how unprepared they were for war with the US and desperately tried to avoid war.

The conspiracy theory is that Spain was responsible for the sinking of the USS Maine using a high explosive mine. I believe evidence points away from Spain being responsible. Spain had no motive for sabotaging the Maine: Spain did not want a war with the US. The physical evidence is very much in doubt but the explosion very possibly may have been an accident. The US never accused Spain of sinking the Maine but many Americans believed Spain to be responsible anyway. The conspiracy isn't completely baseless but I think there is pretty strong evidence that an accidental explosion on board a US Warship was the catalyst that precipitated the Spanish-American War.

The Dolchstoßlegende (Stab-in-the-back legend) that was popular among rightists and, later, Nazis after the first World War was, at best, an extraordinarily creative interpretation of how events actually unfolded. And, how the world suffered because of its popularity.

It wasn't so much that the basic events surrounding the legend didn't happen, but the armistice was quite surely not the result of a deliberate attempt by communists and Jews to weaken Germany to the point where her enemies on the inside and out could finish her off. It started, probably, as a way for demoralized Germans to feel better about how the war turned out, but it soon became a driving force for the radicalization of politics in the country, and in particular, a weapon with which to beat to death the Weimar Republic.