You'd be surprised. Warrior monks are still around. They're not much of a phenomenon, but they still exist.I don't how you could get Buddhist crusades, outside something like an Ikko Ikki controlled Japan. Granted the Ikko Ikki and Japan in general is the only Buddhist area where I've heard of warrior monks as a phenomenon.
From Newsweek, on Thailand:
Amid the violence, security measures have also transformed Buddhist temples. Many government troops in the deep south are based on the sprawling, walled-in temple grounds. Soldiers protect monks and worshippers from insurgent attacks, while benefiting from the monasteries’ existing infrastructure. Buddhist insecurity has even spawned soldier monks—new Army recruits who are pulled aside by superiors and offered a chance to become ordained monks so that they can eventually move to monasteries in the contested provinces and serve as hybrid servants of the state, according to U.S. academic Michael Jerryson. He has dedicated months of field research to the phenomenon, which he says was conceived by the queen.
Monks interviewed in the region today are uncomfortable discussing the soldier-monk practice, which they say has been discontinued. But many of the state’s security measures in the deep south are still channeled through Buddhists and Buddhist spaces, an approach that many analysts say has exacerbated sectarian divisions. “We’ve been saying it’s problematic. It’s like you’re arming people from one religion against another,” says the Crisis Group’s Chalermsripinyorat. Jerryson makes a bolder claim: official policies have generated a Buddhist militant movement in its own right. “International and Thai analysts largely overlook the Buddhists’ call to arms when they attempt to explain the spikes of violence in the war-torn region,” Jerryson writes in his book Buddhist Fury: Religion and Violence in Southern Thailand, published last year. Groups such as Amnesty International have documented cases of soldiers bringing suspected insurgents to temple-housed bases to interrogate, torture, and even execute them. And Chor Ror Bor units have been suspected of engaging in vigilante justice.