Here is an interesting videos by Jesse, the Karate Nerd. He makes some really strong points in this video, the same ones I've made time and time again. However, I do think there are some weak points to his arguments. But, the point that old warriors didn't go to the ground is correct and in self-defense against multiple attackers you need to stay on your feet is absolutely correct also. I don't agree that this video is proof that jiujitsu doesn't work, jiujitsu practitioners can be very skilled. Old-style Japanese jujutsu avoids going to the ground for the express reason that in battle, while wearing armor, you don't want to get locked into a grappling match on the ground because there are so many dynamics in play: broken weapons on the ground, the opposing side's soldiers who may be looking for a new opponent and seeing their comrade in trouble on the ground, etc. In Bujinkan we do have some ground fighting methods, these are called Suwari Gata and are considered a way of dealing with bad situations where we find ourselves on the ground. Just in case...
Shane Sensei is a licensed Shidoshi in the Bujinkan and member of the Shidoshi-Kai. He has trained in the Bujinkan since 1998 and regularly travels to Japan for training.