Tacitus Justinian Constantine ap Howell ap Constantine (1159-1191) was one of the most ambitious of the Grand Princes of Cambria. However, his vision of a united Celtic state under a single ruler would never be realised in his own lifetime.

He was a shrewd politician, as well as a highly capable general.

He succeeded to the kingdom of Strathclyde on the death of his mother in 1182, and to the kingdom of Scotland on the death of his uncle Constantine in 1184. This (amongst other things) spurred him on to unite all of the Celtic kingdoms under his own rule. To that end, following the crushing of an uprising by his cousin, Justinian of Galwyddel, he went to war in Ireland in 1187, taking several of his cousins, including Llewellyn of Gwynedd, who was his lieutenant.

Unfortunately, the war was to be the death of him. After successfully conquering the Kingdom of Meath, as well as accepting the submission of Leinster, he went after the king of Connacht. He died of his wounds following the Battle of Sligeach (Sligo) in March of 1191 (though the Cambrian forces were victorious). On his deathbed, with his final words, he implored his cousin, Llewellyn, to carry on his dream.


Tacitus married Magdalen of South Reged (1161-1219) in 1170.


  • Tacitus Germanus Gerontius (1172-1194); no issue.
Preceded by:
Howell II
Duke of Demetia
Tacitus III
Grand Prince of Cambria
Preceded by:
Mary III of Strathclyde
King of Strathclyde
Preceded by:
Constantine II of Scotland
King of Scotland
Preceded by:
New Title
Duke of Meath
Count of Dublin
Title next held by
David of Gwynedd

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