Masovia is the Piast land on the middle Vistula, the Narew and the Bug, ruled from the castle of Płock, which was the capital of all Poland from 1079 to 1138.
Bolesław III's will of 1138 gave it to his son Bolesław IV the Curly, together with Kuyavia west of the Vistula and the frontier lands of Dobrzyń and Chełmno facing the Prussians. Bolesław IV's son Leszek died childless in 1186 and left it to his uncle Casimir II the Just; Mieszko III the Old took Kuyavia (in 1186, or only in 1194 by some accounts) and gave it to his son Bolesław. When Casimir died suddenly in May 1194, all his lands passed to two small boys, Leszek the White and Konrad, under their mother Helen of Znojmo, who governed with Bishop Pełka (Fulko) of Kraków and the Kraków palatine Mikołaj.
Mieszko III fought them for Kraków: at Mozgawa (13 September 1195) his son Bolesław of Kuyavia was killed. In 1198 Helen let Mieszko have Kraków; in return he gave Kuyavia back to Casimir's sons, who kept Masovia and Sandomierz. In 1199 the Kraków lords threw Mieszko out again, and the struggle for Kraków goes on. On 1 January 1200 Masovia with Kuyavia, the Dobrzyń land and the Chełmno land belongs to Casimir's two sons and is the share marked out for the younger, Konrad, a boy of about twelve.
His mother governs, Leszek (about fifteen) is beginning to rule for himself, and the Masovian lords run the castle districts. The duchy is ruled through castles and their districts (kasztelania) under castellans (kasztelan), with a palatine (wojewoda) at the head of the host, two bishops (Płock, and Kujawy at Włocławek), and no chartered towns. Its northern and eastern edges are forest frontiers facing the pagan Prussians and the Yotvingians (Sudovians).
Casimir II's campaign up the Drwęca in 1191-1193 forced some Prussians to pay tribute, and no raid is recorded for the winter of 1199-1200; the great Prussian devastation of the Chełmno land and Masovia begins in 1216, and Konrad's call to the Teutonic Order comes in 1226.
Who rules
- Name
- Konrad, younger son of Casimir II the Just, a boy of about 12, holding with his elder brother Leszek the White (about 15) the lands their father left; their mother Helen of Znojmo governs
- Title
- duke of Masovia (dux Masoviae), with Kuyavia, the Dobrzyń land and the Chełmno land
- Since
- 5 May 1194 (Casimir II's death): the brothers inherit together under their mother's regency. Masovia is marked out as Konrad's own share in 1199 (en.wikipedia, de.wikipedia) or 'probably in 1200' (pl.wikipedia): not pinned for 1 January 1200. Kuyavia came back to the brothers from Mieszko III under the agreement of 1198.
- Born
- Konrad about 1187/1188, so 11 or 12; Leszek about 1184/1185 (K. Jasiński, 2001; older works say 1186/1187), so about 15
- Family
- Sons of Casimir II the Just (died 5 May 1194; en.wikipedia's Helen page gives 1 May) and Helen of Znojmo, a Přemyslid princess born about 1141/1145, who dies between 1202 and 1206. Their sister Adelaide (about 1177/1184 to 1211) is unmarried and later founds St James's nunnery at Sandomierz; an elder sister married Vsevolod Svyatoslavich, later prince of Kyiv, in 1178. Their brothers Casimir and Bolesław died as children (1167; 1182/1183). Konrad is unmarried and childless: he marries Agafia, daughter of Svyatoslav Igorevich of Novgorod-Seversk, about 1207-1210, and his eldest son Bolesław is born about 1210. Leszek is unmarried.
- Confidence
- medium
pl.wikipedia Konrad I mazowiecki; en.wikipedia Konrad I of Masovia, Leszek the White, Helen of Znojmo, Mieszko III the Old, Bolesław of Kuyavia; de.wikipedia Konrad I. von Masowien
Overlord
None below the pope. The duke of Kraków claims a seniority over all the Piast duchies, but Kraków itself is fought over between Mieszko III the Old and Casimir's sons' party (see the krakow record), and the seniority is hollow.
What the realm holds
- Masovia proper: the castle districts of Płock (the ducal seat), Wyszogród, Sochaczew, Czersk, Ciechanów and Wizna, with lesser castles (Raciąż, Szreńsk, Zakroczym, Płońsk and others) whose state in 1200 is not pinned
- Kuyavia, back from Mieszko III since 1198: the castle districts of Kruszwica, Inowrocław and Włocławek, with Radziejów and the Kuyavian Wyszogród (Fordon) on the lower Vistula
- The Dobrzyń land between the Vistula, the Drwęca and the Skrwa: the castle of Dobrzyń
- The Chełmno land between the Vistula, the Drwęca and the Osa: the castles of Chełmno and Grudziądz, the frontier against the Pomesanian Prussians
- The duke's rights (regalia): markets, tolls at the castles and Vistula crossings, ferries, fisheries, the mint, the forests, and the services owed by the people under Polish law (building and guarding castles, carting, feeding the duke's men and horses)
- Patronage of the churches founded by the dukes; the bishops of Płock and Kujawy hold great estates of their own (Church map)
How it was acquired
Inherited from Casimir II, who received Masovia under the will of his nephew Duke Leszek in 1186. Kuyavia was handed back by Mieszko III in 1198 as part of the price of Kraków.
Allies and rivals
Allies: the Kraków lords who back Casimir's sons (the palatine Mikołaj, Bishop Pełka); the Sandomierz lords (the palatine Goworek, captured at Mozgawa and ransomed); Roman Mstislavich of Volhynia, whom Leszek's troops helped to take Halych (Galicia) in 1199. Rivals: Mieszko III the Old of Greater Poland, who held Kuyavia until 1198 and wants Kraków, and his son Władysław Spindleshanks; the Silesian princes who fought for Mieszko at Mozgawa (Mieszko Tanglefoot, Jarosław of Opole). Pomerelia faces the Chełmno land and Kuyavia across the Vistula: Sambor I at Gdańsk and, opposite the Chełmno land, Grzymisław at Świecie (last attested 11 November 1198; Grzymisław); relations in 1200 not pinned.
The realm that morning
On the morning of 1 January 1200 the castles of Masovia, Kuyavia, the Dobrzyń land and the Chełmno land are held for Casimir II's sons; no enemy holds any of them. Konrad, about 12, is the duke marked out for this share, but his mother Helen governs, and Leszek, about 15, is taking up his own rule (1199 or 1200). The formal division (Sandomierz with the claim to Kraków for Leszek, Masovia with Kuyavia for Konrad) is dated 1199 by some and 'probably 1200' by others: the campaign may treat it as made or as about to be made.
Kraków itself is in dispute (see the krakow record). Across the borders: Greater Poland (Mieszko III) west of Kuyavia, beyond Lake Gopło, Mogilno and the Noteć; Pomerelia across the Vistula from the Chełmno land (Grzymisław at Świecie, Sambor I at Gdańsk) and north of Bydgoszcz; the Pomesanian Prussians beyond the Osa; the Sasinians and Galindians beyond the forests north of Ciechanów and Przasnysz; the Yotvingians beyond the Biebrza and the upper Narew; Rus' Volhynia (Roman Mstislavich) at Drohiczyn and Brest on the Bug; Sandomierz (Leszek's) beyond the Pilica and the Wilga; and the Łęczyca land, part of the senior province of Kraków, between Masovia, Kuyavia and Sieradz (see Łęczyca land).
Wealth
The Vistula trade: grain, salt, timber, furs, wax, honey and captives go down to Pomerelia and Gdańsk, and cloth and Baltic goods come up; the duke takes tolls at Płock, Wyszogród, Włocławek and the crossings. Kuyavia's brine springs give boiled salt (round Kruszwica, whose name is linked to salt blocks, and Inowrocław). Amber and furs come in from the Prussian and Yotvingian lands through the frontier castles. The forests give honey, wax, furs and game; the river meadows feed cattle and horses.
Wealth here is rights over people and their dues and services, not acreage.
Military
Castle levies under the castellans, led by the palatine, with the knights of the great families and the duke's household warriors. The frontier castles are Wizna on the Narew against the Yotvingians, Ciechanów against the northern forests, and Chełmno and Grudziądz against the Pomesanians. The host served Casimir II against the Prussians and Yotvingians in 1191-1193; a Masovian part at Mozgawa (1195) is not recorded. No numbers are known.
Threats
- Mieszko III or his son Władysław Spindleshanks taking Kuyavia back if the Kraków bargain is broken for good
- Prussian raids across the Osa and the Drwęca into the Chełmno and Dobrzyń lands, and from Sasinia and Galindia into northern Masovia (none recorded this winter)
- Yotvingian raids across the Biebrza and the Narew on the Wizna district (in 1196 Roman of Volhynia raided the Yotvingians, who were attacking his borders: en.wikipedia Roman the Great)
- A boy duke and a regent mother: the Masovian lords can make or break the regency
- The war for Kraków pulling Masovian levies and money south
Consort
None. Konrad is unmarried (he marries Agafia of Novgorod-Seversk about 1207-1210). The widowed duchess Helen of Znojmo, about 55 to 59 years old, is the regent.
Heirs
Konrad and Leszek are each other's heirs. Neither has a child on 1 January 1200 (Konrad's eldest son Bolesław is born about 1210, Leszek's son Bolesław the Chaste in 1226).
Regency
Since May 1194 Helen of Znojmo has governed her sons' whole inheritance with Bishop Pełka (Fulko) of Kraków and the Kraków palatine Mikołaj (campaign notes Part 6 I; en.wikipedia Leszek the White). In Masovia the work falls on her, the Masovian palatine and the castellans, none of whom is named for 1199-1200. en.wikipedia (Helen of Znojmo) has Leszek take independent authority in 1199 or 1200; pl.wikipedia has the brothers co-rulers until about 1200. Konrad, at about 12, cannot rule in person: whoever holds the regency for him in 1200 (his mother, his brother, or the Masovian lords) is the campaign's call.
If Mieszko III is back in Kraków on the Kraków lords' terms that morning (the krakow record, Kraków (Mieszko III)), the palatine Mikołaj and Bishop Pełka sit in his Kraków, and the regency that remains over Masovia is Helen's own.
Officers
The palatine (wojewoda) of Masovia: not named for 1200 (Żyron guarded the sickly Duke Leszek of Masovia for Casimir II from 1177; Krystyn is palatine in the 1210s and is killed on Konrad's order in 1217). The castellans of Płock, Wyszogród, Sochaczew, Czersk, Ciechanów, Wizna, Kruszwica, Inowrocław, Włocławek, Dobrzyń and Chełmno: none named for 1200 (the first known castellan of Czersk is Piotr Pilch, in 1224). No Masovian chancellor is known for 1200; the regents' documents would come from the Kraków or Sandomierz court.
Court in 1200
Not pinned. The regent Helen and Leszek are based at Sandomierz, and at Kraków when their party holds it; where the boy Konrad spends the winter is not recorded. Płock castle is the seat of Masovian government, with the bishop of Płock, the palatine and the castellan.
Treaties
The agreement of 1198 between Helen and Mieszko III: Mieszko takes Kraków; he cedes Kuyavia to Casimir's sons; they keep Masovia and Sandomierz (en.wikipedia Mieszko III the Old, Helen of Znojmo, Bolesław of Kuyavia). By some accounts it also named Leszek as Mieszko's successor at Kraków (Kraków (Mieszko III)). The Kraków lords broke it in 1199 by expelling Mieszko, and he came back on their terms (by the reckoning most often given, before the end of 1199: Kraków (Mieszko III), Greater Poland).
No treaty with the Prussians or Yotvingians is known; whether the tribute Casimir II forced on some Prussians in 1191-1193 is still paid is not known.
Feuds
The war for Kraków against Mieszko III the Old (since 1194; Mozgawa, 13 September 1195). It was quieted by the bargain of 1198 and reopened when the Kraków lords drove Mieszko out in 1199; its state on 1 January 1200 is the krakow record's question. No open war on the Masovian frontiers is recorded that winter.
Throne war
The succession to Kraków and the seniority: Mieszko III the Old against Casimir's sons and the Kraków lords. Masovia is not itself claimed by Mieszko after 1198, but Kuyavia was his until then.
Relations with rome
Normal. Archbishop Henryk Kietlicz of Gniezno (since 1199) is a reformer of the pope's school who will press church immunity and free elections and will clash with the dukes (Church map record; campaign notes Part 6 I). The bishops of Płock and of Kujawy (Włocławek) are Church map records. Rome later blesses Konrad's crusade against the Prussians (1209).
Coinage
Silver bracteates, thin one-sided pennies, are Poland's coin in these years; Casimir II and Leszek struck them. A Masovian issue of 1199-1200 and the mint that struck it are not pinned.
The host
Each castle district raises its levy under its castellan; the palatine leads the host; the knights of the great families come with their own followers; the duke's household warriors form the core. No numbers are known.
Church
The bishopric of Płock (with Pułtusk) and the bishopric of Kujawy at Włocławek (with Wolbórz) are Church map records, as is the archbishop of Gniezno's Łowicz. de.wikipedia's lists give Wit of Chotel as bishop of Płock (1187-1206); at Włocławek Onold (1187-1198) is followed by a gap until Stefan (1206-1212), so the bishop of Kujawy on 1 January 1200 is not pinned (the campaign notes mark both sees thin). The left-bank country round Czersk lies in the diocese of Poznań (an archdeaconry of Czersk is recorded later, en.wikipedia Czersk). Houses: the Benedictines of St Adalbert at Płock, the canons regular of Czerwińsk, the collegiate churches of Płock and Kruszwica, the Premonstratensian nuns of Strzelno; the Benedictines of Mogilno on the Greater Poland side draw tithes from Masovian castles (the Mogilno charter dated 1065, a later forgery).
What the year holds
What happened next, if nothing in play changes it. Each event carries what it depends on and what would stop it.
In 1200
- during 1200 (some date it 1199)The brothers divide Casimir's lands: Leszek keeps Sandomierz and the claim to Kraków; Konrad receives Masovia with Kuyavia (pl.wikipedia: 'probably in 1200'). Konrad, still a boy, stays under his mother's and brother's guidance for some years.Depends on: Leszek coming of age, Helen's consent and the Masovian lords' acceptance Stopped by: the death of either boy; a new war with Mieszko III; the Masovian lords refusing a boy duke
- 1200-1202The struggle for Kraków goes on: Mieszko III comes back and holds Kraków until his death (the dates of his return differ; see the krakow record).Depends on: the Kraków lords coming to terms with Mieszko Stopped by: a decisive victory of Casimir's sons' party, or Mieszko's death
Later, on the likely course
- 13 March 1202 (after this year)Mieszko III dies at Kalisz; Władysław Spindleshanks takes Kraków for a time, then the Kraków lords call Leszek. de.wikipedia dates Konrad's rule over Kuyavia (with Sieradz and Łęczyca) from 1202; en.wikipedia puts his receipt of Kuyavia in 1205.Depends on: Mieszko's natural death Stopped by: play changing Mieszko's circumstances
- between 1202 and 1206 (after this year)Helen of Znojmo dies, probably on 2 April.Depends on: natural death Stopped by: nothing in play is likely to change it
- 1205 (19 June in the usual Polish dating; en.wikipedia's Leszek page gives 14 October) (after this year)Leszek and Konrad defeat and kill Roman Mstislavich of Galicia at Zawichost.Depends on: Roman's invasion of Lesser Poland Stopped by: peace with Roman
- 1206-1209 (after this year)Konrad brings Cistercians from Greater Poland to Masovia to preach to the Prussians and Yotvingians (1206); with the pope's consent he leads a crusade against the Prussians in 1209 without success.Depends on: Konrad's own rule and Rome's backing Stopped by: war elsewhere
- 1216-1222 (after this year)Prussians destroy the castle of Chełmno (1216); Konrad and the bishop of Płock hand their shares of the Chełmno land to Bishop Christian of Prussia (1222).Depends on: the Prussian mission provoking the Prussians Stopped by: a strong Masovian frontier defence
Places of note
- Płock castle and cathedral: Ducal castle on the Vistula bluff (Wzgórze Tumskie); the cathedral of the Virgin completed under Bishop Alexander in 1144 (de.wikipedia); bishop's seat since 1075
- Czerwińsk: House of canons regular on the Vistula, a 12th-century foundation of the bishops of Płock (date not pinned here)
- Kruszwica, collegiate church of SS Peter and Paul: Romanesque basilica of about 1120-1140 beside the castle on Lake Gopło (de.wikipedia)
- Włocławek: Seat of the bishops of Kujawy since 1123 (de.wikipedia): Church map record
- Strzelno nunnery: Premonstratensian nuns on the Kuyavian side of the Greater Poland border; Wierzchosława, daughter of Bolesław of Kuyavia, is a nun there (en.wikipedia)
Where the sources disagree
- Date of Konrad's share: en.wikipedia (Konrad I of Masovia) and de.wikipedia (Konrad I. von Masowien) give 1199; pl.wikipedia (Konrad I mazowiecki) says the division was 'probably in 1200'; en.wikipedia (Helen of Znojmo) says Leszek took independent authority in 1199 or 1200. Not pinned for 1 January 1200.
- Kuyavia: en.wikipedia (Mieszko III the Old, Bolesław of Kuyavia, Helen of Znojmo) and pl.wikipedia (Konrad I mazowiecki) have Mieszko III cede Kuyavia to Casimir's sons in 1198; en.wikipedia (Konrad I of Masovia) has Konrad receive Kuyavia only in 1205, and de.wikipedia in 1202 together with Sieradz and Łęczyca. This record follows the 1198 cession: Kuyavia is in the Casimirids' hands that morning, whether held for Konrad or for Leszek. en.wikipedia (Leszek of Masovia) adds that Mieszko's seizure of Kuyavia in 1186 rests on H. Rutkowski's reading, with no direct primary evidence.
- The regents: the campaign notes (Part 6 I) name Bishop Pełka with Helen and the palatine; en.wikipedia (Leszek the White) names Fulko (the same man) and Mikołaj Gryfita. pl.wikipedia (Konrad I mazowiecki) names 'Bishop Gedko', who died in 1185: a slip for Pełka. No conflict with the campaign notes.
- Casimir II's death: 5 May 1194 in the usual Polish reckoning (en.wikipedia Leszek the White); en.wikipedia (Helen of Znojmo) gives 1 May 1194.
- Mieszko III in Kraków in 1199: en.wikipedia (Mieszko III the Old) says the Kraków lords deposed him in 1199 and he returned only under a new settlement in 1202; en.wikipedia (Leszek the White) says he held Kraków 'with a short interruption in 1199' until his death. This decides who holds the Łęczyca land that morning (Łęczyca land). The neighbouring researchers follow the reckoning that has Mieszko back in Kraków before the end of 1199 (Kraków (Mieszko III), Greater Poland), and this file follows them.
- campaign notes Part 6 we make Bishop Pełka co-regent for Leszek with Helen and the voivode. That holds for 1194-1198; if Mieszko is back in Kraków on the Kraków lords' terms on 1 January 1200 (Kraków (Mieszko III)), Pełka and the voivode Mikołaj are in Mieszko's Kraków, and only Helen's regency over Sandomierz and Masovia remains. Worth the campaign's ruling.
- Bolesław of Kuyavia's children: Greater Poland says none are known; en.wikipedia (Bolesław of Kuyavia) gives him daughters only, their number disputed: Eudoxia (Audacia, born about 1190/1195, who marries Henry of Schwerin in 1208), Wierzchosława (born before 1195, a nun at Strzelno in Kuyavia, died about 1212) and perhaps a posthumous daughter who marries Jaczo of Gützkow in 1210/1215. They are Mieszko III's grandchildren, not heirs to Kuyavia.
- The campaign notes mark Płock and Włocławek thin. de.wikipedia's bishop lists give Wit of Chotel at Płock (1187-1206) and, at Włocławek, Onold (1187-1198) followed by a gap until Stefan (1206-1212): the bishop of Kujawy on 1 January 1200 is not pinned, and the see may be vacant.
Evidence: The holders, the regency and the 1198 agreement are well attested in the general histories (resting on Wincenty Kadłubek's chronicle and the Kraków annals), but the date of the brothers' division is disputed and no Masovian or Kuyavian officer of 1199-1200 is named in any source reached. Polish Wikipedia could be read only once during this research; local detail rests on English and German Wikipedia and general knowledge.
On the map: The realm's ground is drawn in the duke's record (Konrad of Masovia) and the castle districts (Płock castellany and the others). The Łęczyca land is drawn separately under the krakow realm (Łęczyca land).
Primary sources for this realm
Chronicles, registers, sagas and inscriptions written in or near 1200 that cover this entry. Each has its own page with editions, translations and where to read it.
- Chronicle of the Poles, by Master Vincent (Wincenty Kadłubek), Wincenty Kadłubek (about 1190 to 1208). Book 4 is a contemporary's account of the fight for the senior throne of Kraków. Read online
- The annals of the Kraków chapter and the other Polish annals (kept from the 11th century; the Kraków chapter annals continued to 1266). Short dated entries that fix the chronology Kadłubek blurs: the deaths of dukes and bishops, Mieszko the Old's captures of Kraków, Prussian raids on Masovia, church consecrations. Read online
Sources and studies
- Wikipedia (pl): Konrad I mazowiecki
- Wikipedia (en): Konrad I of Masovia
- Wikipedia (de): Konrad I. von Masowien
- Wikipedia (en): Leszek the White
- Wikipedia (en): Helen of Znojmo
- Wikipedia (en): Mieszko III the Old
- Wikipedia (en): Bolesław of Kuyavia
- Wikipedia (en): Leszek of Masovia
- Wikipedia (en): Battle of Mozgawa
- Wikipedia (en): Duchy of Masovia
- Wikipedia (en): Old Prussians
- Wikipedia (de): Kulmer Land
- Wikipedia (de): Herzogtum Masowien
Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.