The Livonian Brothers of the Sword (Latin: Fratres militiæ Christi Livoniae, German: Schwertbrüderorden) was a Catholic military order established in 1202 during the Livonian Crusade by Albert, the third bishop of Riga[1][2] (or possibly by Theoderich von Treydend).

The membership of the crusading order comprised warrior monks, mostly from northern Germany, who fought Baltic and Finnic pagans in the area of modern-day Estonia, Latvia and Lithuania.

The Baltic German Livonian Brothers had a set of rules adopted from the Knights Templar, requiring them to be of noble birth and to take vows of obedience, poverty, and celibacy.

[4] The characteristics of the territory brought a moral challenge for the crusaders because the land of the Livs and Letts had not previously been Christian.

As rewards for secular knights in the Baltic area were not enough to ensure their long-term stance, Albert founded the Brotherhood in 1202 to aid the Bishopric of Livonia in the conversion of the pagan Livonians, Latgalians and Selonians living across the ancient trade routes from the Gulf of Riga eastwards.

[4] The Brotherhood had its headquarters at Fellin (Viljandi) in present-day Estonia, where the walls of the Master's castle still[update] stand.

The commanders of Fellin, Goldingen (Kuldīga), Marienburg (Alūksne), Reval (Tallinn), and the bailiff of Weißenstein (Paide) belonged to the five-member entourage of the Order's Master.

[4] In 1206, the Duke Vladimir of Polozk demanded tribute from the inhabitants of the Daugava when the terms of service of the crusaders expired.

Despite that, some native leaders felt that the Order represented a challenge to their authority, as the case of King Vetseke, the original owner of the fortress of Koknese.

The Swordbrothers were the core of the crusader army, allied with Russians, loyal Livs and Letts, and led by Engelbert von Thisenhusen, brother-in-law of Albert of Riga.

[4] Between 1211 and 1212, the Swordbrothers realised that winter was the best season for warfare due to frozen swamps, weak undergrowth, and difficulty of their enemies to cover their tracks.

The Order used these advantages in their campaigns until 1218, when they conquered southern Estonia, meanwhile they beat off counter-attacks from Russians and Lithuanians.

[citation needed] The desires of the Swordbrothers to expand to the north of the Daugava river, along the Livonian Aa stream, brought the Order into a confrontation with Bishop Albert.

Albert wanted to extend to the south of the river and did not have an interest in Estonia, previously promised to King Valdemar II of Denmark.

The papal legate Bernard of Aulne decided that they should be suppressed, and he tried to recapture the Danish Castle at Reval.

[4] Pope Gregory IX asked the Brothers to defend Finland from the Novgorodian attacks in his letter of November 24, 1232.