Morihei Ueshiba, the Japanese inventor of aikido, was tired of witnessing his father getting roughed up by thugs so he set out to train in martial arts. Soon after, he sought refuge in different religions and then later combined his newfound knowledge and ideologies to found aikido in 1942.

Fundamentally, aikido borrows the joint locks and throws from jiu jitsu and merges them with the body transfers of sword and spear fighting. It's often considered the most difficult martial art.