By the summer of 1864, Denmark's position was beyond recovery. The army had been crushed at Dybbol in April and displaced from Als Island days later. The remaining forces had withdrawn north of the Limfjorden and were being evacuated from Frederikshavn. The war over the duchies of Schleswig and Holstein was ending in Prussian victory, and everyone knew it. Lieutenant-Colonel H.C.J. Beck and his First Regiment had been left behind in Norresundby with a rearguard mission: hide the retreat, secure the fjord crossings, and advance southward only if it could be done without disproportionate risk. The last clause was critical. What followed would test whether Beck understood it.

On 1 July, Prussian scouting units pushed north from Hobro. Beck took his Fifth Company south toward Gunderup, where he found a Prussian column stopped in Lundby. His scouts were spotted. The Prussians, about 70 of their 124 men, took cover behind an earth dike at the town's southern edge. From the ancient burial mound of Kongehoj, about 500 meters to the south, a long flat slope descended toward the dike with no cover whatsoever. Beck ordered Captain P.C. Hammerich to lead a bayonet charge straight down the hill. Locals stepped forward to offer alternative routes, an easterly ravine or a westerly approach along fences that would provide some protection. Beck dismissed them all. The company formed half-columns, sixteen men deep, and charged with cheers. The Prussians, armed with modern breech-loading needle guns that could fire far faster than the Danes' muzzle-loaders, delivered three devastating volleys. The first came at 200 meters. The charge collapsed twenty meters from the dike.

The numbers are stark: 32 Danish soldiers killed, 44 wounded, 20 captured, two missing. Three Prussians wounded. The Danes had not even held a two-to-one numerical advantage, far short of the three-to-one ratio military doctrine considered the minimum for a frontal assault. Their muzzle-loading rifles were a generation behind the Prussian breech-loaders, which meant the defenders' effective firepower was far greater than their numbers suggested. The terrain offered the attackers nothing, no cover, no concealment, no angle of approach that might have disrupted the Prussian aim. Every factor favored the defense, and Beck had chosen to ignore them all. The Prussians, for their part, did not pursue the survivors. They withdrew to Hobro, carrying both their own wounded and the Danish casualties, and brought thirteen dead to Gunderup for burial.

What makes Lundby haunting is not just the slaughter but the response. Observers at the time did not regard the outcome as a defeat. Julius Strandberg wrote a patriotic broadside praising Beck's initiative and energy, framing the charge as the kind of bold action expected in war. Beck was promoted to Colonel and made a Commander of the Order of the Dannebrog. Historians have been less generous. Beck was a politician as well as a soldier, and during the First Schleswig War fifteen years earlier, he had been passed over for promotion after Colonel Laessoe criticized his conduct. At the Battle of Sankelmark in February 1864, he had left his unit while it was engaged. The charge at Lundby, some argue, was less about military necessity than about a man trying to restore a damaged reputation, at the cost of his soldiers' lives.

Today a large memorial cross stands at the battlefield, immediately east of the highway. Officers from the Gardehusarregimentet, the regiment that continues the First Regiment's lineage, visit the site each year on the anniversary of the battle. At the cemetery near Gunderup church, a monument marks the graves of the fallen. In Hobro, a separate memorial honors a Swedish officer who volunteered to fight on the Danish side and died of his wounds. The landscape has not changed much. The long, exposed slope from Kongehoj down to the old village edge remains, and standing there you can see exactly what those 160 men saw as they started running: open ground, no cover, and a very long way to go.