Our word of the month is composed of three compounds: Dolch (dagger), Stoß (stab, thrust), and Legende (legend, myth). It means literally "dagger stab legend (or myth)". The phrase has its origin in the aftermath of WWI:
Reactionaries of various stripes claimed that Germany lost the war not on the battlefields, but on the home front, where socialists, communists, liberal democrats, or Jews (i.e. all the usual bugaboos of the German right at the time) "stabbed the fighting troops in the back" by sabotaging the war effort (through strikes, anti-war writings etc.).
The term is now generally used to characterize efforts to assign blame for a lost cause not to the real culprits, but to those that the blamers consider their adversaries. Right now, we can observe a Dolchstoßlegende in the making when we follow right-wing commentators trying to blame the outcome of the recent election not on the deficiencies of the McCain campaign, but on the (alleged) pro-Obama stance of the so-called "liberal media".