Every school kid in Spain knows this sentence makes no sense. Almoravids were the most fanatic sect in Islam. In the year 1212, they gathered an army of 300,000 soldiers to convert Europe by force, but they were repelled by a Christian army of 50,000 at the Battle of Navas de Tolosa (Spain). That was the largest battle in Europe until D-Day.
http://www.youtube.com/watch?v=g8uVevYY88M
Another little point that Mr. Obama seems to forget, is that Muslims were big in the black slaves trade. In fact, at the above referred battle Caliph Al-Nasir chained thousands of black slaves around his tent to fight for him till their death.
Call that tolerance, Mr. Obama? I call it ignorance, if not worse.
As usual with premodern armies, the numbers involved are debatable. Here's a link that references 125,000 for the Muslim side. http://www.nmhcpl.org/uploads/The_Crusade_of_Las_Navas_de_Tolosa_1031.pdf
It is very unlikely any premodern army could have invaded with a force of 300,000. No way to transport sufficient food for men and, especially, the animals to haul that food.
Even with railroads the armies of the Civil War faced great difficulty in provisioning armies that seldom much exceeded 100,000 men.