Throughout history, the Scots and the English have rarely got along. In times past, when the two countries were separated, not only by culture, but also by monarch, the Northumberland borderlands were a dangerous place. There were cattle-raids, feuds, murders and small-scale local skirmishes, of course, but much more serious were the full-scale armies which not infrequently invaded the lands across each border.
In Northumberland, the Scottish threat loomed constantly. The Celtic monarchs always took a great interest in English affairs, as indeed the southerners did in those across the Solway-Tweed divide. There had been a mutual mistrust from the earliest times, when the Saxons first stepped from their boats. The English had never been satisfied with the land they held and for them, expansion was the name of the game. As far as the Scots were concerned, therefore, attack was the best form of defence. Throughout the medieval period and later, the Scottish monarchs were more-or-less forced to associate themselves with England's enemies in order to keep their nation strong: the Welsh, the Vikings, the Lancastrians - or the Yorkists, who cared as long as the English were divided - and, of course, the 'auld alliance' with the French.
The Battle of Hexham
Whether through invasion or other forms of assistance given by the Scots to England's adversaries, it was the border which made Northumberland one of the most favoured battlegrounds in England.