o own his
supremacy, and slightly increased by conquest the area of the mark.
Otto's son, Otto II., was the succeeding margrave, and having quarrelled
with his powerful neighbour, Ludolf, archbishop of Magdeburg, was forced
to own the archbishop's supremacy over his allodial lands. He died in
1205, and was followed by his step-brother, Albert II. (c. 1174-1220),
who assisted the emperor Otto IV. in various campaigns, but later
transferred his allegiance to Otto's rival, Frederick of Hohenstaufen,
afterwards the emperor Frederick II. His sons, John I. and Otto III.,
ruled Brandenburg in common until the death of John in 1266, and their
reign was a period of growth and prosperity. Districts were conquered or
purchased from the surrounding dukes; the marriage of Otto with
Beatrice, daughter of Wenceslaus, king of Bohemia, in 1253, added upper
Lusatia to Brandenburg; and the authority of the margraves was extended
beyond the Oder. Many monasteries and towns were founded, among them
Berlin; the work of Albert the Bear was continued, and the prosperity of
Brandenburg formed a marked contrast to the disorder which prevailed
elsewhere in Germany. Brandenburg appears about this time to have fallen
into three divisions--the old mark lying west of the Elbe, the middle
mark between the Elbe and the Oder, and the new mark, as the newly
conquered lands beyond the Oder began to be called. When Otto died in
1267, the area of the mark had been almost doubled, and the margraves
had attained to an influential position in the Empire. The
_Sachsenspiegel_, written before 1235, mentions the margrave as one of
the electors, by virtue of the office of chamberlain, which had probably
been conferred on Albert the Bear by the German king Conrad III.

Otto IV.

In 1258 John and Otto had agreed upon a division of their lands, but the
arrangement only took effect on Otto's death in 1267, when John's son,
John II., received the electoral dignity, together with the southern
part of the margraviate, which centred around Stendal, and Otto's son,
John III., the northern or Saltzwedel portion. John II.'s brother, Otto
IV., who became elector in 1281, had passed his early years in struggles
with the archbishop of Magdeburg, whose lands stretched like a wedge
into the heart of Brandenburg. In 1280 he was wounded in the head with a
dart, and as he retained there a part of the weapon for a year, he was
called "Otto with the dart." He secured the appointm