One reason why the St. George legend has such staying power is that the dragon can stand in for any bad thing. As we celebrate the centenary of the end of the First World War, here are a couple of examples of how he was employed in the propaganda of both sides:
This one, by an unknown artist, was published in London by Spottiswoode and Co. in 1915 for the Parliamentary Recruiting Committee.
Wikipedia
And this one, by Maximilian Lenz, was published in Vienna in 1917 for the sixth war bond campaign of the Austro-Hungarian Empire.
In both cases one’s own army is cast as the good St. George, and the enemy as the evil dragon. I suppose it’s a good thing that British and Austro-Hungarian troops did not face each other directly all that much, otherwise St. George might not have known what side to take! (Last Saturday, Sasha Volokh asked, in seriousness, what happens when two powers dedicated to St. George fight against each other, e.g. Russia and Georgia in 2008. I said that I did not know, but I suppose it only really matters if people actually believe in the power of saints as heavenly intercessors and not just as mascots or symbols – and even then I suppose it’s no different from both sides believing in God and praying to him for victory.)
These posters raise a serious point though. I like St. George, obviously, but sometimes the legend does promote self-righteousness. We all like to believe that we’re in the right, and the other side is in the wrong, but we must keep in mind that this might not always be the case! But since there can be no compromise between good and evil, the Manichaeism on display here, I think, would tend to discourage people from seeking a negotiated settlement, and to encourage them to keep digging, even though they’re already in a hole.