Anno has no relation to the Princes of Brunschweig, as wrote it an historian, and none with the free and playful chivalry of the German Empire. As Bart, Salza and Wüllersleben, he came from a family of bailiffs from Landgrave in Thuringia, of which the city of Sangerhausen was probably the principal domain.
We know only few things about his family, even if Jutta von Sangerhausen, venerated as the angel of Chełmno were his parent. Some people consider her as the sister or the mother of the future Grand Master.
Anno suddenly appears in the history of the Teutonic Order in 1254 as Master of the Province of Livonia. He replaced Eberhard von Sayn with determination, because during his reign Teutonic knights won a lot of battles there. The properties of the Teutonic Order lie along the eastern Baltic Sea and spread from Pomerania to Livonia. Lithuanians were at peace with the Teutonic Order, and along the banks of the Niemen River, expanded the new stronghold of Klajpeda. Anno von Sangerhausen contributed significantly to the building of this fortress and when it was attacked by Samogitians, he rushed to its rescue, and with a lot of bloodshed he pacified the entire region of Samogitia.
In June 1256, Anno had to go to Rome to attend the General Chapter convened by the Grand Master of the Order, Poppo von Osternohe, who resigned under circumstances still unclear to this day. Some time later, probably during the Chapter convened in Frankfurt-am-Main some months later, Anno von Sangerhausen was elected new Grand Master of the Teutonic State.
After a few years of relative peace, Samogitians attacked Livonia with the help of Lithuanian King Mendoga (Mindaugas). In September 1260 in Prussia, all the tribes revolted against the Order and Aleksander Newski, prince of Novgorod, left the city of Psków to besiege the Teutonic castle of Dorpat. All those oppressed by the Teutonics attacked them and the Order narrowly escaped this onslaught. It lost most of its castles and kept only those along the rivers and the cove of the Vistule.
To save the Order in mortal danger, Anno von Sangerhausen launched a diplomatic offensive across Europe and especially at the papal court, where he managed to obtain the summons by pope Urbain IV of all Crusaders across Central Europe. The Pope requested their assistance in fighting the pagans of the North, and even offers absolution to all who committed offences in their country if they helped the Teutonic Knights. Thanks to this call, Anno was able to quickly return to Prussia in January 1263 with a sizeable troop of cavalry particularly from the Rhineland.
After this first success, Anno starts to recruit everywhere in Europe, but especially in Germany, in his native Thuringia, in Brandenburg, Franconia at the princes of Brunszwik, in Altenberg, Marburg, Quedlinburg, Eger, Regensburg. He even goes to Bohemia and Austria, and no doubt thanks to all this energy, new knights arrive non-stop in Prussia. The other result of his efforts was the creation of 16 new preceptories in Europe such as for example in Venice, St-Leonardo, Mottling and Eger, from which the Order drew a lot of money for its military actions in the East.
When in 1265, the pope Clement IV asks again for assistance for the Teutonic Order, even Prince Albert I of Brunszwik, Landgrave Albert II of Thuringia and Margrave Otto III of Brandeburg come to its help. But it is the expedition of Margrave Dytryk II which devastated Natagia and carried the most serious blow against Prussia in 1272. As of that moment, Teutonics began to take back the lands lost previously and, around 1274, they seized Lidzbark and push back resistance beyond the bordering areas of the Teutonic State.
Anno von Sangerhausen died on July 7th or 8th 1273 in Germany without seeing the definite triumph of the Order. One doesn't know neither the exact place of his death nor of his burial. Chroniclers say that it would be in Trier or in Mergentheim.