"Christian I (c. 1130 – 23 August 1183), sometimes Christian von Buch, was a German prelate and nobleman. He was Archbishop of Mainz and Archchancellor of Germany from 1165 until his death 1183. He was originally elected archbishop in 1160 in a disputed election. He served the Emperor Frederick I as a diplomat in Italy on two occasions." - (en.wikipedia.org 31.01.2020)
