I'm glad the Fujiwara family is marrying into our family.
We just let the Fujiwara take control of the entire country!
JAPAN IS MINE!
The emperor held power in Japan for some time. That time didn't last as the Fujiwara family married into the emperor's family. This made it so that the Fujiwara held all the real power.
The capital will burn in the name of the Minamoto!
Soon, the Taira and Minamoto clans become jealous. Both raise armies and plan the take down the Fujiwara. The combined number of troops was enough to take down the Fujiwara.
We have to go. the Minamoto are coming.
When the Taira and Minamoto attack, they are an unstoppable fighting force. They take down the Fujiwara, ridding the Fujiwara of all heir power. They will never recover.
You are now the shogun. Use this position responsibly.
Now, the Minamoto had too much power. With this power, they went to the capital of Japan, Kyoto. Kyoto burnt in the name of Minamoto Yoritomo.
With the Fujiwara no longer in control, the Minamoto turned their back on the Taira. What the young emperor did not know when he boarded the Taira fleet was it would be his last day. The Minamoto attacked the fleet and the young emperor jumped off the boat to prevent capture. Never was the emperor seen again.
Now that the emperor was not in power, Minamoto Yoritomo became shogun or supreme military commander. This position was only meant to be temporary. Yoritomo changed this and held the position permanently.