Two months earlier, at Heiligerlee, Louis of Nassau had won the first real victory of what would become the Dutch Revolt. His brother Adolf had been killed in that battle, but the rebels had bloodied a Spanish army and given the Low Countries something to hope for. Louis had pressed on, trying to take Groningen, but he had failed. Then Fernando Álvarez de Toledo, the Duke of Alba, arrived from Brussels with twelve thousand infantry in four veteran tercios and three thousand cavalry. Louis had ten thousand men - mostly German mercenaries - and sixteen cannons. He took up a strong position near Jemgum, where the flooded fields of the Reiderland and the Ems itself made a wall on his flank. He believed the terrain would protect him. It would do the opposite.

Alba did not commit his whole army. Only 3,500 Spanish troops crossed the flooded fields, water up to their knees, aiming for a single bridge over a lock that controlled the rebel position. Captains Marcos de Toledo, Diego Enríquez and Hernando de Añasco led the assault with pikes and arquebuses. They took the bridge. Louis sent four thousand men to retake it from a Spanish detachment of fewer than fifty. The fifty held until two veteran tercios arrived - the Old Tercio of Lombardy under Juan de Londoño and the Old Tercio of Sicily under Field Marshal Julián Romero. The German mercenaries fled. The tercios chased them, then halted, suddenly outnumbered, at the Dutch front line. Romero and Londoño begged Alba for reinforcements. Alba refused. He left them there as bait. When Louis took the bait and threw his whole army forward, Spanish arquebusiers waited until the range was right and then opened fire. The line broke. The rout began.

What followed was not a battle anymore. The retreating mercenaries ran for the rivers and the canals, and the Spanish followed them, killing for hours. Six thousand men died on the Dutch side that day. Many of them did not die fighting; they died trying to cross water in armour, or trying to surrender, or simply trying to keep moving. They had names and families in Hesse and Saxony and the Low Countries that we will mostly never know. Louis of Nassau survived only because he stripped off his armour, took on a disguise, and swam. Alba, the cold tactician who had used his own veterans as bait, would later be cast in bronze - literally. In May 1571 his statue was erected in the citadel of Antwerp, made from one of the captured Dutch cannons. The Eighty Years' War had only begun. It would last until 1648. The army that drowned at Jemgum was just the first.

The Antwerp statue lasted six years. After the Sack of Antwerp in 1576, when Spanish soldiers mutinied and slaughtered thousands of civilians, the city joined the revolt it had been keeping at arm's length. In 1577, a crowd pulled down the bronze Duke of Alba - cast from the cannons his enemies had abandoned at Jemgum - and broke him apart. The killing field on the lower Ems is quiet farmland now. Polders, dikes, canals. The Ems still flows past Jemgum, tidal and slow. If you look at the ground at the right time of year you might find iron from that day. Most of what fell here was flesh, and the river carried it away.