The defeat of the English at Ancrum Moor forced King Henry VIII to adopt a new strategy for dealing with the Scots. Instead of launching border raids and trying to pressure the Scots into marrying their child queen, Mary Queen of Scots, to an English prince, Henry decided on a purely military option.
The new war plan envisaged a large English army marching into Scotland to capture key towns, cities and fortresses. These were to be garrisoned with strong bodies of English troops and supplied from the sea by the newly powerful English Royal Navy. There would be no attempt to rule Scotland or to occupy its more rugged areas. Instead, the English-held strongpoints would disrupt attempts to muster an army while English money would be used to bribe the various factions of nobles into continuing their disputes.
In this way Henry hoped to keep Scotland in turmoil and unable to invade England. Henry died in January 1547 and left the plan to his nine year old son, the boy-king Edward VI.
As Edward was unable to rule the kingdom, Henry had put a Regency Council in control, led by the Duke of Somerset. Somerset was King Edward’s uncle, being his mother’s brother. He also had plans to usurp the powers of the Council and become sole Protector of England. To do this he needed prestige, and he looked for a military victory in Scotland to give it to him.
Declaring he was merely carrying out the dying wishes of Henry VIII, Somerset called a muster of English soldiers for the end of August in Berwick. Then he hired a force of European mercenaries, who could be relied upon to be loyal to himself as the man paying them, and marched north to take command. At Berwick Somerset met up with the Earl of Bothwell, the Earl of Cassilis and other Scottish nobles who opposed the Earl of Arran’s government. In the harbour Somerset had a fleet of 32 merchant ships laded down with all the supplies his army would need and 30 warships armed with the heaviest cannon available.
On September 1st, Somerset marched north. He moved slowly, anxious to avoid the notoriously successful Scottish ambushes and raids. At Coldingham Moor, on the Lammermuir Hills, a party of Scottish scouts was seen and Somerset halted the army until his own scouts drove them off. At Tantallon Castle, Somerset bypassed the defences and pressed on. On the 8th September the English army crested Falside Hill and looked down into the valley of the Esk, with Edinburgh beyond. Drawn up in battle array on the far bank of the river was a Scottish army. It was obviously larger than his own, so Somerset gave orders to halt. He put his men into defensive positions along the Falside ridge while he consulted his officers about what to do next.
The Scots army was confident of success, and with good reason for, despite their internal differences, Scotland had rallied to face the invader. The Regent, the Earl of Arran, had persuaded the majority of the nobles to bring their men to the mustering in front of Edinburgh. The Earl of Huntly had brought the Highlanders, Lord Home had brought the Borderer light cavalry and the Earl of Angus, victor of Ancrum Moor, had come with all his men.