The ninth century saw the decline of Mercia as a kingdom. In 873-74 Mercia was conquered by the heathen army. In the 880s Wessex formed a marriage alliance with Mercia. Alfred's daughter, Ethelflaeda, married Ethelstan (II), of Mercia. When Ethelstan died, in 912, Edward the Elder appointed Ethelflaeda (his sister) 'Lady of the Mercians.' When Ethelflaeda died in 918, the Mercian nobles now thought themselves free of Wessex rule. Edward stepped in and appointed Ethelflaeda's daughter, Aelfwynn, to rule Mercia as his representative. But in 919 Edward brought her back to Wessex. After that Mercia was considered just another shire under his rule. A series of (similar to a count in Europe) followed. Under Canute in 1017, Mercia became one of the four divisions of England.