I heard this stated as a fact. I know there have been territorial disputes eg Turkey/Greece over Cyprus, Pakistan/India over Kashmir but has there ever been a full scale war between two democracies?
Do civil wars count?
How about the 1982 war between Britain and Argentina over the Falkland Islands? With regards to the “full scale” qualifier, I suggest you ask the casualties.
Could 1982 Argentina truly be called a democracy?
And I’d guess we’d want to limit this to functioning democracies, as Hitler was elected.
“Fascist dictatorship” would be more like it!
Depends on how you define monarchy. Was Britain in 1812 a monarchy with democratic overtones? How about in 1862, when they nearly went to war with the US over the takeover of one of their ships (Confederate representatives were aboard and taken off; there were Union hawks who actually advocated starting a war with Britain, as if Lincoln didn’t have enough troubles already.)
Then, what about the various India-Pakistan conflicts? India is certainly a democracy, while Pakistan has moved back and forth between that and rule-by-generals.
BTW, Argentina was under rule-by-generals in '82, and IIRR, losing the war was instrumental in bringing them down.
erislover has a point. Couldn’t it be said that a democracy once went to war with itself? Didn’t a democratic United States once war with a democratic Confederate States?
no, because thats a war between one democracy.
As noted, Hitler was elected. And Yugoslavia was/is a democracy–or is that not a full-scale war? I think the truth of the “fact” depends on how the terms are defined.
Once the war began (1939), Germany was a Totalitarian state, the Nuremberg laws having been passed in 1933.
So that rules out Nazi Germany.
Yugoslavia was not a democracy, it was history. What was in its place was chaos. No go.
An extremely good article on this very subject.
Quote from the referenced site:
I think he’s mentioned all possible democracy v. democracy wars, no matter how obscure (cod wars?) and he argues with himself. Very cool. 
Here’s his take on the Kosovo War:
I took Yugoslavia to mean the Soviet-era bloc nation, not Croatia. And I do consider Milosovic to be a dictator, albeit a smart one.
So there!
Well, whether it should count or not depends on what the premise of the OP is. If it’s just a technical point of interest, then maybe it doesn’t count. But if the point is to make the claim that democracies won’t get into wars with other democracies, then the civil war would be a valid counter-example.
But even if you can’t find a ‘legitimate’ example it doesn’t prove anything other than that we haven’t had two democracies see a need to fight each other. Democratic government hasn’t been around all that long, especially in large numbers. So it may just be an accident of geography or a fluke of foreign relations that has kept the world’s democracies from attacking each other. Or it may be that most countries that became democratic were fostered by other democratic countries, and therefore were natural allies.
It doesn’t seem inconceivable to me that we could wind up at war with say, India.
Upon reflection, would the Spanish-American war count? I’m trying to recall the exact form of the Spanish government. It wasn’t a pure democracy, but it was a constitutional monarchy with established opposing political parties, wasn’t it?
I didn’t mean Croatia–I meant the federation (or whatever it is) of Serbia and Montenegro–you know, Yugoslavia.
Milosevic may have been a dictator, but he was elected in a contested election. And then he lost an election…
So there! right back atcha…
Well, here’s what my reference says: “In Spain, “the two major political parties alternated in power, not by election but by arrangement preceding elections.””
So, if you call that a democracy (and I don’t), I guess so.
Oh, OK. That’s right. Serbia and Montenegro … yeah. Thanks. 
The only reason Milosevic left office was international pressures. In a democracy, peaceful transitions of power should happen without NATO breathing bullets down your neck.
What about the Boer War, where Britain was basically at war with the republics of Transvaal and Orange Free State?
I’m not sure how democratic any of those three countries were by today’s standards. EG, no votes for women.
On a vaguely related note, didn’t McDonald’s used to claim that no 2 countries with McDonald’s restaurants had ever been to war with each other? I think the ex-Yugoslav chaos made this claim redundant.
Not a democracy without universal suffrage, you say? I guess that eliminates the Peloponnesian War.
But Sparta wasn’t really a democracy anyway, since the assembly didn’t really have power.
I think the point about the rarity of two democracies going to war is that in a democracy the assembly or an executive drawn from that assembly has to approve the war, and this is less likely than would be the case in a dictatorship or military oligarchy like Sparta.
The Lacadaemonians (Spartans) were a gerontocracy, not a democracy, in any event.