The execution of Charles I in January 1649 had pulled Scotland in two directions at once. The Scottish Parliament, never consulted about the killing of its king, had promptly declared his son Charles II to be King of Britain and set about raising an army to put him on the throne. Cromwell's response, in July 1650, was invasion. By September the Scottish army under David Leslie lay broken at Dunbar - 6,000 prisoners, 1,500 dead or wounded, Leslie's reputation in tatters. In the aftermath, the more dogmatic Covenanters drew an unforgiving lesson. God had abandoned the army, they argued, because the army had not been sufficiently purged of impure men. The remedy was more purging. They issued the Western Remonstrance, took control of the Western Association army, and prepared to fight both the English and their own government.

Colonel Gilbert Ker led the Remonstrants south through a country wet with early winter. At Hieton, on rising ground above the Cadzow Burn where it joins the Clyde, he caught Lambert's English troopers off-guard and attacked at dawn. The surprise worked - briefly. The Scots broke into the English position before Lambert's veterans steadied, regrouped, and counter-charged. Cavalry against half-formed cavalry, on ground neither side had chosen, in the cold light of a December morning. The Remonstrant army did not so much retreat as dissolve. Ker himself went down wounded and was taken prisoner. The Western Association ceased to exist as a fighting force before the sun was high. There would be no godly remnant to wrest Scotland back.

Hieton was a small fight in a much larger war, but its consequences were immediate. With the Western Remonstrants destroyed, the Scottish government's hand was forced. The radicals were finished, and the army would be rebuilt by whoever was willing. The following summer Cromwell forced his way across the Firth of Forth, won at Inverkeithing, took Perth, and cut the Scottish army off from supply. In desperation, Charles II and Leslie marched south into England, hoping for an English rising that never came. At Worcester on 3 September 1651, exactly a year after Dunbar, Cromwell crushed them. Charles escaped, famously hiding in an oak tree, and fled abroad. He would not see Britain again until the Restoration of 1660.

Today the field of the Battle of Hieton lies under Hamilton's Common Green, a sliver of public grass tucked beside the town centre. The 19th-century Cadzow Bridge crosses overhead, and a modest plaque mounted on the bridge by Hamilton Civic Society tells passers-by that men once died here for a quarrel about how purely a king's army ought to be raised. Most people walking past do not stop. The burn still runs the same line it did in 1650, and the rise above it still earns its old Scots name of Hieton - the high town - even if no one calls it that anymore.