The Order of Brothers of the German House of Saint Mary in Jerusalem was formed to aid Christians on their pilgrimages to the Holy Land and to establish hospitals.

[6] Pope Clement III approved it and the Order started to play an important role in Outremer (the general name for the Crusader states), controlling the port tolls of Acre.

[13] After the loss of Jerusalem in 1187, some merchants from Lübeck and Bremen took up the idea and founded a field hospital for the duration of the Siege of Acre in 1190, which became the nucleus of the order; Pope Celestine III recognized it in 1192 by granting the monks Augustinian Rule.

This castle, which defended the route between Jerusalem and the Mediterranean Sea, was made the seat of the Grand Masters in 1229, although they returned to Acre after losing Montfort to Muslim control in 1271.

During Frederick's coronation as King of Jerusalem in 1225, Teutonic Knights served as his escort in the Church of the Holy Sepulchre; von Salza read the emperor's proclamation in both French and German.

In 1224, the Teutonic Knights, seeing that they would have problems when the Prince inherited the Kingdom, petitioned Pope Honorius III to be placed directly under the authority of the Papal See, rather than that of the King of Hungary.

This was a grave mistake, as King Andrew, angered and alarmed at their growing power, responded in 1225 by expelling the Teutonic Knights, although he allowed the ethnically German commoners and peasants settled here by the Order to remain and these became part of the larger group of the Transylvanian Saxons.

This being a time of widespread crusading fervor throughout Western Europe, Hermann von Salza considered Prussia a good training ground for his knights for the wars against the Muslims in Outremer.

[15] With the Golden Bull of Rimini, Emperor Frederick II bestowed on the Order a special imperial privilege for the conquest and possession of Prussia, including Chełmno Land, with nominal papal sovereignty.

Bishops were reluctant to have pagan Prussian religious practices integrated into the new faith,[20] while the ruling knights found it easier to govern the natives when they were semi-pagan and lawless.

[22] The Order ruled Prussia under charters issued by the Pope and the Holy Roman Emperor as a sovereign monastic state, comparable to the arrangement of the Knights Hospitallers in Rhodes and later in Malta.

To make up for losses from the plague and to replace the partially exterminated native population, the Order encouraged immigration from the Holy Roman Empire (mostly Germans, Flemish, and Dutch) and from Masovia (Poles), the later Masurians.

[23] Although the Northern Crusades were aimed at pagan Balts and Finns, rather than Orthodox Russians, several unsuccessful attempts were made to persuade Novgorod to convert to Catholicism after the capture of Tartu.

[25] Hoping to exploit Novgorod's weakness in the wake of the Mongol and Swedish invasions, the Teutonic Knights penetrated deep into Novgorodian territory;[25] however, in 1242, they were defeated in the Battle of the Ice at the hands of Prince Alexander Nevsky.

The Livonian Rhymed Chronicle describes the events:[26] There is a city in Russia called Novgorod, and when its king [Alexandre] heard what had happened he marched towards Pskov with many troops.

[30] The conflict had much influence in the political situation of the region and was the source of many rivalries between Lithuanians or Poles and Germans; the degree to which it impacted the mentalities of the time can be seen in the lyrical works of men such as the contemporary Austrian poet Peter Suchenwirt.

Overall, the conflict lasted over 200 years (although with varying degrees of active hostility during that time), its front line extending along both banks of the Neman River, with as many as twenty forts and castles between Seredžius and Jurbarkas alone.

During the reign of Grand Master Winrich von Kniprode (1351–1382), the Order reached the peak of its international prestige and hosted numerous European crusaders and nobility.

King Albert of Sweden ceded Gotland to the Order as a pledge (similar to a fiefdom), with the understanding that they would eliminate the pirating Victual Brothers from this strategic island base in the Baltic Sea.

An invasion force under Grand Master Konrad von Jungingen conquered the island in 1398 and drove the Victual Brothers out of Gotland and the Baltic Sea.

In 1407, the Teutonic Order reached its greatest territorial extent and included the lands of Prussia, Pomerelia, Samogitia, Courland, Livonia, Estonia, Gotland, Dagö, Ösel, and the Neumark, pawned by Brandenburg in 1402.

These terms had not been fulfilled by the time of the Treaty of Schönbrunn in 1809, and therefore Napoleon Bonaparte ordered the Knights' remaining territory to be disbursed to his German allies, which was completed in 1810.

There were three Landmeisters: Because the properties of the order within the rule of the Deutschmeister did not form a contiguous territory, but were spread over the whole empire and parts of Europe, there was an additional regional structure, the bailiwick.

Although the reconstruction represented by the reformed Rule of 1929 had set aside categories such as the knights, over time the spontaneous involvement of laypeople in the Order's apostolates has led to their revival in a modernized form, a development formalized by Pope Paul VI in 1965.

The approximately 100 Catholic priests and 200 nuns of the Order are divided into five provinces, namely, Austria, Southern Tyrol-Italy, Slovenia, Germany, Czech Republic and Slovakia.

By the end of the 20th century, then, this religious Order had developed into a charitable organization and established numerous clinics, as well as sponsoring excavation and tourism projects in Israel.

In 2000, the German chapter of the Teutonic Order declared bankruptcy, and its upper management was dismissed; an investigation by a special committee of the Bavarian parliament in 2002 and 2003 to determine the cause was inconclusive.

[60] According to medieval historian Erik Christiansen, "Himmler's plan to mould the SS as a reincarnation of [The Teutonic Order] proved [...] the irresistible strength of bad history.

[62] After Hitler approved the Generalplan Ost (GPO), Germanization campaigns were extolled as the modern adaptation of what it portrayed as "civilizing missions" of the Teutonic Order.

This occurred mostly due to Hitler's and Himmler's belief that, throughout history, Catholic military-religious orders had been tools of the Holy See and as such constituted a threat to the Nazi regime.