Pope Gregory IX was a formidable canon lawyer and a great patron of the military orders, who in 1237 incorporated the shattered Livonian Brothers of the Sword into the Teutonic Order.
Pope Gregory IX (reigned 1227–1241) was one of the most energetic and combative of medieval popes — a brilliant lawyer, a fierce champion of papal authority, and a key patron of the crusading orders in the Baltic and the Holy Land.
Born Ugolino, of the counts of Segni and a kinsman of Pope Innocent III, he trained in law at Bologna and Paris and served as a cardinal and papal legate before his election in 1227.
Gregory was aged but astonishingly vigorous, a man of iron will and legal genius. He compiled the Decretals that became the backbone of Church law for centuries, and he pursued his aims — the supremacy of the papacy, the suppression of heresy, the support of the crusades — with relentless energy into his nineties.
His combativeness defined his reign. He excommunicated the Emperor Frederick II twice and fought him to the end of his life, and in 1231 he established the papal Inquisition to root out heresy, appointing the first inquisitors. Firm to the point of harshness, he was also a genuine patron of the new religious movements, canonising both Francis of Assisi and Dominic.
For the military orders he was a decisive friend: it was Gregory who, in 1237, folded the remnant of the Sword-Brothers into the Teutonic Order after their destruction at Saule, shaping the future of the Baltic crusades.
Gregory worked closely with Hermann von Salza, the Teutonic Grand Master, and it was under his authority that the Livonian Brothers of the Sword were incorporated into the Teutonic Order in 1237, creating its autonomous Livonian branch.
He confirmed privileges for the Templars and Hospitallers and pressed for renewed crusade, treating the military orders as essential instruments of the Church.
Gregory died in Rome in August 1241, in extreme old age, with Frederick II’s forces closing on the city — unbroken in his war with the emperor to the last.
Gregory IX left the Church a codified body of law, a permanent machinery of inquisition, and a reinvigorated crusading effort. For the Baltic, his merger of the Sword-Brothers into the Teutonic Order set the shape of the northern crusades for centuries.
He is remembered as one of the great lawyer-popes and as an implacable defender of papal power against the empire.