Arnold holds the western half of the Altena inheritance: the new castle of Isenberg above the Ruhr at Hattingen, his share of Altena on the Lenne, and lands and rights on the lower Ruhr and the Lippe, including the castle of Nienbrügge (Novus Pons) on the Lippe west of Hamm (date of building not pinned).
As the archbishop's brother he is a pillar of Cologne's party and of Otto's.
Who he is
- Name
- Arnold of Altena
- Title
- Count of Altena
- Since
- 1180, on his father's death
- Born
- probably before 1150
- Family
- Son of Count Eberhard I of Berg-Altena; brother of Archbishop Adolf of Cologne and of the late Count Frederick of Altena. Wife: Mechthild (died 1223), daughter of Count Floris III of Holland. Children named in the genealogies: Eberhard, Frederick (the later count of Isenberg), Dietrich (later bishop of Münster), Engelbert (later bishop of Osnabrück), Philipp, Bruno, Gottfried, Adolf, Agnes and Wilhelm; their birth years are not pinned and some may be born after 1200.
- Confidence
- medium
Founder of the Isenberg line of the house of Berg-Altena. He built Isenberg castle on the hill west of Hattingen between about 1193 and 1199; a charter of 1200 first names it as 'castrum Ysenberg'. He sold his share of the family castle of Altena to his brother the archbishop around 1200 (exact date not pinned). He was among Otto's supporters at the coronation at Aachen in July 1198. He dies on 3 May 1209 (some sources give 1206 or 1207).
Overlord
Allodial lord with fiefs of the Cologne church; brother of the archbishop.
What it holds
- Isenberg castle above the Ruhr west of Hattingen (built about 1193-1199)
- His share of Altena castle on the Lenne, shared with his nephew Adolf (sold to the archbishop around 1200: not pinned)
- Nienbrügge on the Lippe west of Hamm (attested later; date of building not pinned)
- Manors and rights on the lower Ruhr round Hattingen
How it was acquired
Inheritance of Eberhard I (died 1180), divided between Arnold and Frederick at a date not pinned.
Allies and rivals
His brother the archbishop; his brother-in-law by marriage Count Dirk VII of Holland (Mechthild's brother); his sister's husband Simon of Tecklenburg. Neighbours: the count of Berg (lrh), the abbeys of Essen and Werden (lrh), his nephew Adolf.
How things stand that morning
On 1 January 1200 Arnold holds Isenberg and his Altena share and stands with his brother for Otto. Across his borders: Berg and the abbeys of Essen and Werden to the west (lrh), Cologne's Volmarstein to the south, his nephew's lands to the east, the Vest of Recklinghausen (lrh) and Münster to the north.
Wealth
Manors on the lower Ruhr. No figures.
Military
The castles of Isenberg and (his share of) Altena; vassals and ministeriales. No numbers.
Threats
- The cost of building Isenberg
- Family division with the Mark line
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.
- about 1200 (not pinned)Arnold sells his share of Altena castle to Archbishop Adolf.Depends on: His need for money and his move to Isenberg. Stopped by: A breach with the archbishop.
Places of note
- Isenberg castle: Arnold's new castle above the Ruhr.
- Altena castle: Family castle shared with the Mark line.
Where the sources disagree
Evidence: Dates of the castle and of his marriage are good; the division of the Altena lands and the Essen advocacy in 1200 are not pinned.
On the map: The Isenberg share of the Altena inheritance is not mapped in any source for 1200; only the castles are drawn.
Primary sources for Empire
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.
- Annals of Marbach (compiled to 1238, the section on 1198 to 1210 written in the early 13th century). Alsatian annals on the Staufen side of the Upper Rhine. Read online
- Annals of Reiner of Saint James, Liège, Reiner of Liège (1197 to 1230, kept year by year). Contemporary annals kept inside Liège. Read online
- Chronicle of Burchard of Ursberg, Burchard of Ursberg (about 1229 to 1230, reworked by Conrad of Lichtenau). Written a generation later by a fierce partisan of the Staufen and a critic of Innocent III. Read online
- Chronicle of Otto of St Blasien, Otto of St Blasien (about 1209 to 1210). A Swabian continuation of Otto of Freising written from the Staufen side. Read online
- Chronicle of Reinhardsbrunn; Chronicle of St Peter's, Erfurt (Erfurt chronicle in the 13th century; Reinhardsbrunn compilation about 1340 to 1349 from older annals). The two Thuringian chronicles. Read online
- Chronicle of the Slavs, by Arnold of Lübeck, Arnold of Lübeck (about 1209 to 1210). Arnold continues Helmold and writes from Lübeck, close to Danish, Welf and Baltic affairs. Read online
- Royal Chronicle of Cologne (in stages from about 1175 to about 1250; the section on 1198 to 1220 written soon after the events). The fullest German narrative of the throne war from the Welf and Cologne side. Read online
- Chronicle of Hainaut, Gislebert of Mons (about 1195 to 1196). Ends in 1195, so it has no 1200 entries, but it is the indispensable background for Flanders and Hainaut: the career of Count Baldwin V of Hainaut (VIII of Flanders), his union of the two counties, the settlement with Philip over Artois, the rights, castles, fiefs and vassals of Hainaut listed by a man who ran its chancery, and the youth of Baldwin IX, who held both counties in 1200. Read online
8 more in the sources library for The Rhineland, the Low Countries and the Swiss Lands.
Sources and studies
- Arnold von Altena, de.wikipedia
- Isenburg (Hattingen), de.wikipedia
- Adolf I. von der Mark, de.wikipedia
- Study of Archbishop Adolf I of Cologne, ch. III: Adolf as author of the double election of 1198 (pp. 20-37), digitised by ULB Düsseldorf
Last revised 4 November 2026. Published 4 November 2026. Suggest a correction on the OMNIA Discord.