10th century in Denmark

• Gorm the Old, 940–958
• Harald Bluetooth, 940–986
• Sweyn Forkbeard, 986–1014

910s

• 911 – The Vikings settle in Normandy

940s

• 940 – Around this year, Harald Bluetooth becomes king, ruling with his father Gorm the Old.^[2] Bluetooth will later impose Christianity on his people.^[3]

• 942 – William I, Duke of Normandy offers asylum to Harald, and restores him to his throne by force. William I is assassinated later that year.^[4] However, the "Haigrold" described by the chronicler was possibly King Harald Greycloak of Norway or different Viking.^[5]

• 947 – The Norwegian Eric Bloodaxe is elected King of York. He is deposed when the English king Eadred marches north, and flees to Denmark.^[6]

• 949 – Eric Bloodaxe returns from Denmark to England. He will be killed in battle in 952.^[6]

950s

• 950 – Gorm the Old conquers most of Denmark.^[7]
• 950 – Denmark under Gorm's son Harald Bluetooth conquers Norway.^[8]

• 958 – Gorm the Old dies^[9] and Harald Bluetooth becomes sole king, succeeding his father.^[10]

960s

• c. 965 – Harald Bluetooth raises the larger Jelling Stone, taking credit for the unification of Denmark and Christianizing the Danes.^[11]
• 965 – Tartushi visits Hedeby.^[12]

970s

• 970 – the wedding of Harald Bluetooth and Tove of the Obotrites

• 974 – Hedeby falls to the Holy Roman Empire

• 975 – Harald Bluetooth tries to force Christianity upon Haakon Sigurdsson, who then turns against him.

980s

• 980s – Viking raids against England resume during the minority of Æthelred the Unready.^[13]
• 980 – Struggling to unite Denmark, Harald Bluetooth builds at least four large circular forts around this time.^[14]
• 980 – Harald Bluetooth builds the first church in Zealand at Roskilde.^[15]

• 983 – Hedeby returns to Denmark from the Holy Roman Empire.

• 984 – The ladies of Denmark give their gold and silver ornaments to the Jutlanders in exchange for the release of Sweyn Forkbeard.^[16]

• 987 – Eric the Victorious, king of Sweden, expels Sweyn Forkbeard.^[16]

• 988 – First known mention of Odense in writing.^[17]
• 988 – Sweyn seizes power from his father, Harald Bluetooth.^[18]

• c. 910 – Gunnhild, Mother of Kings (died c. 980 in Orkney)
• c. 948 – Valtoke Gormsson (died 986 in Sweden)

• c. 960 – Sweyn Forkbeard (died 1014 in England)
• c. 990 – Cnut the Great (died 1035 in England)
• c. 997 – Harald II of Denmark (died c. 1018)

• c. 958 – Gorm the Old (born before 900)
• c. 988 – Reginbrand