Battles have rarely been massive charges from two sides of a flat battlefield, as we see in war movies. Historically, it's been really hard to get soldiers to charge to their deaths, which makes sense if you think for a second. Most armies throughout history were nonprofessionals levied by their lords or seasonal opportunists, who fought for extra income. Sometimes, the leaders would get the soldiers drunk before they went in, and they'd retreat and have to be coaxed into running in again.<p>Aside from all this, contrary to some sort of received chivalric ideal of loyalty and fighting-unto-death, a great number of military engagements in every part of the world were decided by bribery and deception. People don't want to risk their lives and are often tempted by monetary gain. Countless forts have fallen to people opening the doors from within. There's instances of Sufi leaders being admitted into forts only to open the gates. Hyderabad was conquered by Aurangazeb in great part due to bribery, too.<p>The calculus changes dramatically if the attacker has a history of lenient behavior toward those who surrender, versus massacre for those who do not. The Mughals regularly incorporated surrendering lords into their feudal system, with honors, income, and opportunities for social advancement. The Mongols razed the Khwarezmia because of their disastrous refusal of their envoys.