Historia Regum Britanniae
Scholars have speculated that the legitimacy of Cador's battles can be found through the "Anglo-Saxon Chronicle", presumably written by Alfred the Great. Since there is only one named British Commander, Vortigern, scholars have aligned the timelines in the "Anglo-Saxon Chronicle" and the "Historia Regum Britanniae" to assess the legitimacy of Cador. Many similarities between the battles can be noted. There is an encounter in York, or along the Canterbury-London road with anywhere between 3,000 and 4,000 British soldiers. Here, Arthur and the British retreat to London in both versions of history. The next battle with the supposed Cador is in Thanet, which is noted in both "Anglo-Saxon Chronicle" and "Historia Regum Britanniae". The British Commander in the "Anglo-Saxon Chronicle", despite being unnamed, is speculated to be the Cador in "Historia Regum Britanniae" because of the similarities.