The word comes from the Latin palus, a stake, by way of palisade - the fenced boundary inside which a particular law ran. The Pale of Calais was the small region of coastal France enclosed by English fortifications: Calais itself, the citadel, the ring of outer forts at Guines, Sangatte, Marck, Hammes, and the marshy hinterland between them. Its borders were ill-defined because they ran through wetlands, but the rough area was a triangle perhaps fifteen miles wide at its widest. It was the only place in mainland France that, after the Treaty of Bretigny in 1360, remained part of the realm of the English king. Within it, two languages were heard daily: English in the streets, Flemish among the weavers and traders. The town's old name in English was "Cales," which now survives only in the family name of generations of merchants who imported their wool through it.

England's medieval economy was wool. Wool went to Flanders to be woven into the cloth that clothed western Europe. Calais was the bottleneck. The Calais Staple - the legal monopoly that funneled all English wool exports through the town - was an institution as important to fifteenth-century England as any port authority has ever been. It paid for the war. It paid for the garrison. The town carried a peacetime garrison of 1,400 men, virtually a small standing army, under a Captain of Calais who answered directly to the king. Edward III minted gold quarter-nobles inside the walls between 1361 and 1369. The mint was a statement: this is England. The Channel is forty miles wide here at most. By sea the town could be reinforced from Dover in hours. By land it could be defended from a ring of fortresses against any approach a continental rival cared to make.

The Pale survived two centuries less because England was strong than because France and Burgundy could not agree which of them ought to have it. The Duchy of Burgundy, in its long fifteenth-century ascendancy, sat just to the north. The Kingdom of France sat to the south and east. Each preferred an English Pale to a Pale belonging to the other. So the English stayed, garrisoning, repairing walls, paying the wool merchants of the Staple, and watching the politics of two larger neighbours. Sieges came and went: Burgundy tried in 1436 and failed; an English coup defended it from a French bribe in 1350; raids and skirmishes around Ardres and Guines were almost constant. The walls held. The Pale outlasted the Hundred Years' War itself; by 1453, when the rest of England's French possessions had collapsed back to the Crown of France, Calais was still flying the leopards and lilies of an English king.

What broke the Pale was a strategic failure that began with the Sieges of Boulogne. Henry VIII had taken Boulogne in 1544; in 1550 the Crown, in a financial crisis around the succession of Edward VI, gave it back. With Boulogne French again, the southern approach to Calais lay open. The death of Charles V and the division of Burgundian territory between France and Spain ended the convenient three-way stalemate that had protected the Pale. Then, in 1557, Mary I, married to Philip II of Spain, joined her husband's war against France. The French got there first. Francis, Duke of Guise, organised the campaign in secrecy. In the first week of January 1558, thirty thousand French troops appeared in front of Calais. The garrison was caught understrength. The town surrendered after eight days. The Treaty of Cateau-Cambresis in 1559 confirmed the loss. After two hundred and eleven years, the English flag came down.

Mary I lived ten more months. In England the loss was blamed on her - on her Spanish marriage, her foreign war, her perceived neglect of the realm. Protestant resolve hardened against her. The economic blow turned out to be lighter than feared: the wool trade simply rerouted to the Habsburg Netherlands and the cloth merchants kept working. But the symbolic blow could not be lightened. The deathbed line Holinshed recorded is probably more poetic than literal; it has nonetheless been quoted for four and a half centuries because it tells the truth of what Calais had meant. It was not a possession. It was a part of England that happened to be on the wrong side of a strait. When it went, the medieval idea of an English realm with continental territory ended. After 1558, England would be an island. Three hundred and eighty-two years later, in the same town, three thousand British soldiers would hold the same walls against a panzer division to buy time for the Dunkirk evacuation - a strange echo of a place that had spent half its history being English.