Although he’s well-regarded as a military leader for having retaken Jerusalem from the Crusaders in 1187, Saladin’s military career was certainly not without its setbacks. He appears, for example, to have been mostly outclassed as a battlefield commander by Richard the Lionheart during the Third Crusade, though Richard’s practical limitations in terms of men and materiel, as well as pressures from back home, prevented that Crusade from achieving its ultimate goal of capturing Jerusalem again. And then there’s the 1177 Battle of Montgisard, in which Saladin’s first attempt at capturing Jerusalem was decisively ended in what is now central Israel by an outnumbered Crusader army under King Baldwin IV. Baldwin is one of the most remarkable of all the Crusaders in my humble opinion–after all, they didn’t call him the “Leper King” for kicks. That he survived long enough to rule Jerusalem at all is pretty incredible; that he not only ruled, but was able to lead (successful) armies in the field is really astounding.
Just how badly the Christians were outnumbered is anybody’s guess, because medieval sources only count the number of knights in Baldwin’s army, and that only amounted to something shy of about 400 men, many of them Knights Templar warriors. Obviously Baldwin didn’t defeat Saladin’s army, variously listed at anywhere from around 8000 to 26,000 men, with 400 guys, and we know that medieval European armies included lots of fighters, both on foot and on horse, who were not knights–but nobody bothered to count those fighters in this case. But it seems likely that they were, in fact, pretty significantly outnumbered. They were so badly outnumbered that when Baldwin attempted to stop Saladin’s march toward Jerusalem at Ascalon, Saladin simply detached part of his army to occupy Baldwin and kept right on marching.
In fact, Saladin’s overconfidence about the relative size of his own army seems to have been part of his undoing. Instead of making a beeline for Jerusalem, which was obviously the main prize both from a tactical and religious standpoint, Saladin decided to take his time and nab a couple of the towns and fortresses along the way. Meanwhile, Baldwin was able to shake free of the troops Saladin left at Ascalon and go after the main body of Saladin’s army. The two forces met somewhere near Ramla, a strategically important point that sat at the crossroads of the Cairo-Damascus highway and the main road from Jerusalem to its port at Jaffa (today it’s an Israeli city of about 70,000 people).
Saladin was preoccupied trying to dislodge his baggage train from a muddy patch, and the arrival of Baldwin and his army apparently took him totally by surprise. His army was scattered all over the place, some working on the baggage train and others out foraging for supplies and raiding in the countryside. Baldwin was no dummy, so there was no “let’s do the honorable thing and wait for our enemy to get ready before we attack” bullshit; he ordered his men to immediately charge. We’re told that Baldwin, as weakened as he was by his condition, fought right alongside his men, and if you know anything about , say, Henry V and the Battle of Agincourt in 1415, you know that a king who participates in the fighting like that can inspire his army to great feats (although, if you know anything about, say, Vladislaus I of Hungary and the Battle of Varna in 1444, you know that such a king can also wind up getting killed and throwing his army into disarray).
Saladin managed to hop on the back of a fast camel and vamoose, but his army was cut to pieces. His losses can’t be accurately measured, but estimates are that he brought about one tenth of his army back to Egypt with him, and while some of the 90% he lost may have been due to desertion, I think it’s safe to say that the vast majority were killed. Unfortunately for the Crusaders, Saladin’s position in Egypt and Syria was a whole lot stronger than theirs in Jerusalem and the other Crusader states, and it only took him a couple of years (until 1179) to build up a new army and start harassing the Crusaders again. In 1182 he launched a new campaign to capture Jerusalem; it took five years, but, aided by the fact that Baldwin finally succumbed to his illness in 1185 and was eventually succeeded by a moron, this new effort finally proved successful.