France had not so much invaded the Netherlands in June 1672 as walked into it. Louis XIV crossed the Rhine at Tolhuis on 12 June with one of the largest armies Europe had assembled in a century. Town after town surrendered without a shot - Arnhem, Doesburg, Zutphen, Utrecht - their walls obsolete, their garrisons hopelessly outnumbered, their burghers terrified of what a sack would mean. By July the French held more than half the Republic. The Dutch government collapsed. Johan and Cornelis de Witt, the grand pensionary and his brother who had governed the country for two decades, were torn apart by a mob in The Hague on 20 August. Power passed to twenty-one-year-old William III of Orange, named stadtholder by terrified provinces who wanted any leader who might fight. The Republic was in ruins, but the Republic had not fallen. The Hollandse Waterlinie - dikes broken, polders flooded knee-deep across a north-south corridor west of Utrecht - had stopped the French advance cold.

By mid-September William wanted action. The French were dug in across most of the eastern Republic, but their garrisons were thin. The town of Woerden, just north of the Waterlinie, sat in a vulnerable salient. The Duke of Luxembourg, who had taken over the French occupying army after the Prince of Condé fell out of royal favor, knew it was exposed. The Dutch plan was to draw him away. Johan Maurits, an aging veteran prince of Nassau-Siegen, marched his troops out of Muiden in a feint toward Naarden, a French-held fortress that was indeed undermanned. Luxembourg took the bait. He shifted forces to defend Naarden, and the road to Woerden opened up. William III moved his main army toward the town. From the east came a separate column under Frederick Nassau de Zuylestein, William's uncle and one of the army's most reliable field commanders. From the south came Willem Adriaan with a third column approaching Goejanverwellesluis.

On the night of 11 October the three Dutch columns closed on Woerden. William's troops launched the main assault on the town itself. Zuylestein took up a blocking position on the eastern approaches to intercept any French relief. The town began to fall. But Luxembourg had recovered faster than the Dutch expected. He swung his force south from Naarden through the dark, found the line of the Dutch advance, and probed for a way through Zuylestein's position. His first attack was repulsed. Then a scout found a gap. Luxembourg pushed cavalry and infantry through the breach and struck Zuylestein's troops in the rear. Heavy fighting followed on ground the Dutch could not hold. Zuylestein was killed in the action along with around six hundred soldiers under his command. The French lost more than two thousand of their own dead and wounded, with combined losses exceeding 2,600. The Dutch broke off the assault on Woerden and withdrew. The town remained French.

Zuylestein's death was a personal blow. He had been William's uncle, his guardian and teacher in youth, and the senior field commander the army could least afford to lose. Command passed to William's other cousin, Prince Georg Friedrich of Waldeck, who would steer Dutch armies for the rest of the war. The strategic results were worse than the casualty list. Luxembourg, vengeful and free to move now that the Dutch winter offensive had failed, rampaged through the small villages south of Woerden later that winter. His troops slaughtered the inhabitants of Zwammerdam and Bodegraven in atrocities that the Dutch press would remember for generations. The Rampjaar deepened into a season of named villages and counted dead. And yet William III treated Woerden as a small kind of victory. The Dutch army, written off as a broken instrument three months earlier, had marched in the night, deceived a French marshal, captured most of a town, and held its ground long enough to inflict losses three times its own.

The historian Olaf van Nimwegen has compared the Dutch action that night to Thermopylae. The parallel is generous - Zuylestein's men were not three hundred Spartans, and Luxembourg was not Xerxes - but the political effect was real. The myth of French invincibility had survived the spring, the summer, the September stalemate at the Waterlinie. It did not survive Woerden. Word spread through the Republic that French soldiers could be killed by Dutch ones, that French marshals could be tricked, that the army of the Sun King was, as William himself put it, made of mere mortals. The next year the war turned. Imperial troops joined the Dutch coalition. William marched south to besiege Maastricht. The Republic that had lost almost everything in 1672 would, a decade later, place William III on the throne of England and become the financial center of Europe. None of that was visible on the field outside Woerden on 12 October. But the long arc started there.