The genocide of the Armenians killed far more people than the Albigensian crusade. Wikipedia says 500,000 people were killed, but that comes from a very bigoted source, on that claims that the Dominicans were founded to kill off the Albigensians, although Wikipedia corrects that nonsense. Unfortunately, nearly every source I can find seems to be tracing to that same source, or is from the same brand of pagan that insists that tens of millions of witches were burned by the Catholic Church. (The Catholic church didn't burn witches.)
The two battles which seem to be bt far the most horrific saw the deaths of 10,000-20,000 each. Such figures are easier to find for the individual battles. A few of them note that some estimates of the dead are as high as 100,000. I am tempted to believe that Wikipedia's source (a Languedoc tourist site!) uses those high estmates; it's hard to see how the other battles (a few hundred dead here, a few hundred dead there) add up to more than a few tens of thousands.
Fewer people were around in the 13th century
And the killing it wasn;t just battles
Say 200,000 MURDER BY GOVERNMENT
>>The genocide of the Armenians killed far more people than the Albigensian crusade.
Rummel puts the numbers at 15,000 to 60,000 in 1209, and another 3,000 in 1236. He's always seemed extremely even-handed and thorough.
http://www.hawaii.edu/powerkills/DBG.CHAP3.HTM