I sometimes wonder as I post these things, whether everybody else knows this stuff already. But to continue with our theme of uncles, I never realised that Uncle Sam's initials are U.S., or United States; and though nobody is utterly sure of the origin, the OED says
The suggestion that it arose as a facetious interpretation of the letters U.S. is as old as the first recorded instances, and later statements connecting it with different government officials of the name of Samuel appear to be unfounded.
So there. I set off to do a bit of research and started reading an 1816 book called The Adventures of Uncle Sam in Search of his Lost Honour, but aside from the phrase "Thus ejaculated the chief steward" it's terribly tedious. It does, though, have a nice bit at the beginning about how important it is for a book to be printed, otherwise:
Deeds of fame hard earned in iron fields of argument flutter on to future times, like the treaties of savages, on the tongues of women, mutilated, distorted, exaggerated and defrauded of half their beauty...
Which seems a terribly ungentlemanly attitude towards the tongues of women. Speaking of books being in print, did I mention that my book - The Etymologicon - is being published in three and a bit week's time? Did I mention that it's filled with all sorts of fascinating and entrancing etymological tales? Did I mention that you can pre-order it from this site with free shipping to anywhere in the world?
I did? Oh well.
This says "Friends-Democrats, Uncle Sam and Ivan". It's from a Tsarist pro-American propaganda campaign that started in 1917, and was then cut short.