Konrad I of Masovia

Konrad I of Masovia (Konrad I Mazowiecki) (1187? – 31 August 1247), from the Polish Piast dynasty, was the sixth Duke of Masovia from 1194 until his death as well as High Duke of Poland from 1229 to 1232 and again from 1241 to 1243.

Life
He was the youngest son of High Duke Casimir II the Just of Poland and Helen of Znojmo, daughter of the Přemyslid duke Konrad II of Znojmo (ruler of the Znojmo Appanage in southern Moravia, part of Duchy of Bohemia). His maternal grandmother was Maria of Serbia, apparently a daughter of the pre-Nemanjić župan Uroš I of Rascia.

After his father's death in 1194, Konrad was brought up by his mother, who acted as regent of Masovia. In 1199 he received Masovia and in 1205 also the adjacent lands of Kuyavia. In 1205, he and his brother, Duke Leszek I the White of Sandomierz, had their greatest military victory at Battle of Zawichost against Prince Roman the Great of Galicia–Volhynia. The Ruthenian army was crushed and Roman was killed in battle. The Rurik princess Agafia of Rus became his wife.

Attempted conquests of Prussia
In order to enlarge his dominions, Konrad unsuccessfully attempted to conquer the adjacent pagan lands of Chełmno in Prussia during a 1209 crusade with the consent of Pope Innocent III. In 1215 the monk Christian of Oliva was appointed a missionary bishop among the Old Prussians, his residence at Chełmno however was devastated by Prussian forces the next year. Several further campaigns in 1219, 1222 failed, instead Konrad picked a long-term border quarrel with the Prussian tribes.

The duke's ongoing attempts on Prussia were answered by incursions across the borders of his Masovian lands, while Prussians were in the process of gaining back control over the disputed Chełmno Land and even threatened Konrad's residence at Płock Castle. Subjected to constant Prussian raids and counter-raids, Konrad now wanted to stabilize the north of his Duchy of Masovia in this fight over the border area of Chełmno.

Teutonic Order
Thus in 1226, Konrad, having difficulty with constant raids over his territory, invited the religious military order of the Teutonic Knights to fight the Prussians, as they already had supported the Kingdom of Hungary against the Cuman people in the Transylavanian Burzenland from 1211 to 1225. When they notified Hungary that the Order was firstly responsible to the pope, the Knights were expelled by the Hungarian king Andrew II though. Thus, in turn for the Order's service, Grand Master Hermann von Salza wanted to have its rights documented beforehand, by a deal with Konrad that was to be confirmed by the Holy Roman Emperor and the Roman Curia.

Emperor Frederick II issued in March 1226 the Golden Bull of Rimini, stating that:
 * "brother Konrad had offered and promised to furnish brother Herrmann, Honorable Master of the Holy Hospital of St. Mary of the Germans in Jerusalem (Teutonic Order).. with the Culmensis Land between his march and the Prussians and equip them (T.O.) well, so they may take Preussenland (Terra Prussiae) in possession... we recognize the fact, that this land is included in the realm of the empire, we trust the judgement of the Master... we recognize all land in Prussia as an ancient right of the empire ...".

So far the Knights were not convinced to take the trouble of fighting the Prussians, and on the advice of the first Prussian bishop Christian of Oliva, in 1228 Konrad founded the loyal Order of Dobrzyń instead, calling for another Prussian Crusade - and was again defeated. In view of an imminent Prussian invasion, Konrad supposedly signed the Treaty of Kruszwica in 1230, according to which he granted Chełmno Land to the Teutonic Knights and the Order of Dobrzyń. By this donation disclaiming any enfeoffment, Konrad established the nucleus of the State of the Teutonic Order. The document does not exist however, and it is believed that it was never signed and the Order might have forged it. The Knights under the command of Hermann Balk crossed the Vistula river and conquered Chełmno Land, erecting the castle of Toruń (Thorn) in 1231. In 1234, Pope Gregory IX issued the Golden Bull of Rieti, confirming the prior deals with the Teutonic Knights, stating that the land of the Order was only subject to the Pope, not a fief of anybody.

High Duke
Konrad was also entangled in the conflict over the Polish Seniorate Province with his Piast cousin Duke Władysław III Spindleshanks of Greater Poland and assumed the title of a Polish High Duke in 1229. However their Silesian relative Duke Henry I the Bearded finally prevailed as High Duke at Kraków in 1232 and confined Konrad's rule again to Masovia. When Henry's son and heir, High Duke Henry II the Pious was killed at the 1241 Battle of Legnica, Konrad once again assumed the senioral title, but had to yield to the claims raised by his nephew Bolesław V the Chaste, son of his elder brother Leszek, two years later.

Marriage and children
Between 1207 and 1210 Konrad married Agafia of Rus, daughter of Prince Svyatoslav III Igorevich. They had the following children:
 * 1) Boleslaw I of Masovia (c. 1210 – 17 April 1248), Duke of Masovia (1247–1248)
 * 2) Casimir I of Kuyavia (born between 1210 and 1213 – died 14 Dec 1267) Prince of Kuyavia (1247–1267)
 * 3) Siemowit I of Masovia (c.1213 – 24 June 1262), succeeded eldest brother as Duke of Masovia (1248–1262)
 * 4) Eudoxia (1215–1240), married Count Dietrich I of Brehna and Wettin
 * 5) Ludmila (born before 1225)
 * 6) Ziemomysł (born between 1216 and 4 Jul 1228 – died between 10 July and 18 September 1241)
 * 7) Salomea (born between 1220 and 1225 – died after 30 August 1268), nun
 * 8) Judith (born between 1222 and 1227 – died 4 Dec between 1257 and 1263), married firstly to Duke Mieszko II the Fat of Opole, secondly to Duke Henry III the White of Wrocław
 * 9) Dubrawka (c. 1230–1265)
 * 10) Mieszko (b. 1235), died in infancy.

Konrad's legacy
Konrad is blamed by Poles, that 'his actions began the process whereby the Teutonic Knights came to control much of the Baltic coastline through their monastic state, that had ultimately dire consequences for the Polish state'. From the Polish point of view, the Emperor had no legal basis to vest the Order with lands that were beyond his discretionary power.

King Casimir III of Poland had to accept the rule of the Order in Thorn and Kulm by the 1343 Treaty of Kalisz. After the Thirteen Years' War in the 1466 Second Peace of Thorn, the Polish king Casimir IV Jagiellon gained control over the Chełmno Land as part of Royal Prussia.