April 18, 796. Æthelred of Northumbria killed by Ealdred
April 19 - May 13, 796. Osbald succeeds to Northumbria
May 14, 796. Eardwulf succeeds to Northumbria
May 26, 796. Eardwulf consecrated king of Northumbria at York
The Chronicle notes that there was an eclipse of the moon on 28 March, that Eardwulf succeeded to Northumbria on 14 May, and that he was afterwards consecrated and enthroned on 26 May at York by Archbishop Eanbald and the bishops Æthelberht, Higbald and Badwulf. This is the second recorded consecration of a king in Anglo-Saxon England, after that of Ecgfrith of Mercia in 787. The violence that had attended the Northumbrian succession over the previous forty years showed that it needed all the additional sanctification it could get.
Simeon of Durham adds that Æthelred was killed near the Cover (a river in Yorkshire) on 18 April, and that the nobleman Osbald (perhaps the same as the one involved in the burning of Beorn in 779) was appointed by some nobles of the nation and after 27 days was deserted and banished, fleeing to Lindisfarne and then to the Pictish court. Alcuin wrote a letter to Osbald (EHD 200) which shows that he was suspected of being a party to Æthelred's death, and urged him to turn from secular to religious affairs. This he seems to have done, for Simeon notes that he was an abbot when he died in 799, and was buried at York.
While Osbald may have helped to plan the deed, it was one Ealdred who actually killed King Æthelred, and one of Æthelred's followers, Torhtmund, killed Ealdred in vengeance for his slain lord. We learn this from a letter of Alcuin to Charlemagne of 801 (EHD 206), in which Alcuin provides introductions for several Englishmen who wished to visit Charlemagne's court, Torhtmund among them. Simeon records Torhtmund's killing of Ealdred in his annal for 799.
Eardwulf had been an ealdorman in Æthelred's reign, and narrowly escaped execution in 791/2. In his own reign (796-806), Eardwulf faced a battle with some of his nobles in 798, ordered the deaths of what might have been rival claimants in 799 and 800, went to war with Coenwulf of Mercia in 801, and was driven into exile in 806.
Alcuin seems initially optimistic about Eardwulf's reign, or at least hopeful that Eardwulf will avoid making the mistakes of his predecessors (see Alcuin's letter to Eardwulf, EHD 199), but he soon returns to the gloom he showed in earlier reigns (see entry on 790). In a letter of 797 (EHD 202) Alcuin notes that Eardwulf dismissed his wife and took a concubine and that he might expect to lose his kingdom soon as a result; in a letter of 801 (EHD 207) Alcuin sympathises with the archbishop of York about his tribulations and makes dark hints about the death of kings who opposed the church.