Anybody know where the phrase “tinpot dictator” came from? Were there once countries with copper-pot dictators who looked down on the tinpots?
OED1 has tinpot meaning 'resembling a tinpot in quality or sound; hence contemptuously, without solid worth, of inferior quality.
First cite in this sense is 1865. I don’t know when it was first applied to dictators, the phrase isn’t in OED1, so it probably is later than the 1920s. We’d need OED2/3 to track down a first cite.
Tin-pot used as an adjective to mean “cheap, inferior” goes back to at least the 1830’s. That’s using the on-line OED.
In general, you don’t find it used referring to dictators until the 1940’s.
I found a newspaper cite from 1906 which said “tin-horn dictator.” Same meaning I think.
I believe it refers to a child playing at being a soldier by wearing a tin pot for a helmet. It emphasises the dictator’s inflated view of himself.
Whether this is true or not, I like the image it conjures the best. I think it captures the flavour of the term really well.
This is what I’ve always thought. I hadn’t known about the earlier meaning.
The child-wearing-a-tin-pot explanation reminds me of I, Claudius (or maybe it was Caligula) where the Emperor was called ‘Little Boots’ because he liked to play at being a soldier by wearing soldier’s boots that were too big for him. (Reminds me of a current leader, who shall remain nameless. 
)