Rudolf 's father consolidated his position by marrying the Habsburg princess Agnes ( 1257 -- 1322 ) whom he had elected King of the Romans in 1273 .
Agnes ( 1257 -- 1322 ) is a daughter of King Rudolf I of Germany .
Rudolf 's father consolidated his position by marrying the Habsburg princess Agnes ( 1257 -- 1322 ) , a daughter of King Rudolf I of Germany , whom he had elected King of the Romans in 1273 .