Why was it important that pope leo iii named frankish king charlemagne "emperor of the romans" in 800ce?

When Charlemagne was named “Emperor of the Romans,” it simultaneously symbolized Charlemagne's importance and the power of the Catholic Church. For Charlemagne, being associated with the greatness or the Roman Empire- by the Pope, no less- let all of Europe know that his power invoked the memory and legacy of Rome. For the Church, it showed people that the titles it bestowed on people still carried weight and influence.

c. troops marched forward in close formation against newer, more accurate weapons

he was able to speed up production of the processing of seeds