After the 1236 Battle of Saule the surviving members of the Brothers merged in 1237 with the Teutonic Order of Prussia and became known as the Livonian Order. In 1346 the Order bought Danish Estonia. Throughout the existence of medieval Livonia there was a constant struggle over supremacy, between the lands ruled by the Church, the Order, the secular German nobility and the citizens of the Hanseatic towns of Riga and Reval. Following its defeat in the Battle of Grunwald in 1410 the Teutonic Order and the Ordensstaat fell into decline but the Livonian Order managed to maintain its independent existence. In 1561, during the Livonian war, Terra Mariana ceased to exist. Its northern parts were ceded to the Swedish Empire and formed into the Duchy of Estonia, its southern territories became part of the Grand Duchy of Lithuania — and thus eventually of the Polish–Lithuanian Commonwealth — as the Duchy of Livonia and the Duchy of Courland and Semigallia. The island of Saaremaa became part of Denmark.
Since the beginning of the 20th century Terra Mariana (Estonian: Maarjamaa) has been used as a poetic name or sobriquet for Estonia. In 1995 the Order of the Cross of Terra Mariana, a state decoration, was instituted to honor the independence of Estonia.
The lands on the eastern shores of the Baltic Sea were the last part of Europe to be Christianized by the Roman Catholic Church. In 1193 Pope Celestine III called for a crusade against the pagans in Northern Europe. This crusade is often compared to the crusade of the Franks and Charlemagne. However, this crusade was not officially announced until 1197 or 1198, but the first account of this crusade is in a letter by Pope Innocent III. At the beginning of the 13th century, German crusaders from Gotland and the northern Holy Roman Empire conquered the Livonian and Latvian lands along the Daugava and Gauja rivers. The stronghold of Riga (capital of modern Latvia) was established in 1201, and in 1202 the Livonian Brothers of the Sword was formed as a branch of the Knights Templar. In 1218 Pope Honorius III gave Valdemar II of Denmark free rein to annex as much land as he could conquer in Estonia. Additionally Albert of Riga, leader of the crusaders fighting the Estonians from the south, paid a visit to the German King Philip of Swabia and asked permission to attack the Estonians from the North. The last to be subjugated and Christianised were Oeselians, Curonians and Semigallians.
This crusade differed from many other crusades because, in this case, the Pope allowed people intending to go on a crusade to the Holy Land to go instead to crusade in Livonia. Members of this crusade were made to wear the insignia of the cross as well, which showed that they were legally bound to the crusade.
This division of medieval Livonia was created by Papal Legate William of Modena in 1228 as a compromise between the church and the Livonian Brothers of the Sword, both factions led by Germans, after the German knights had conquered and subdued the territories of several indigenous tribes: Finnic-speaking Estonians and Livs, and Baltic-speaking Latgalians, Selonians, Semigallians and Curonians.