Rey sealed off the breach with internal defenses, manned the nearby buildings with marksmen, and zeroed in his artillery on the threatened area. At dawn on 25 July, Graham's attack went forward. The mine exploded, doing some damage, but the French easily drove off the southern Allied attack, which was only a diversion. Led by the Royal Scots, the main column splashed across the Rio Urumea estuary at low tide and assaulted the breach from the east. After the attackers reached the top of the breach, the French opened fire and the result was a massacre. The stunned British infantry stampeded, carrying away their supporting battalions. The attackers suffered a loss of 600 killed and wounded, while French casualties were only one-tenth as great. When the incoming tide threatened to drown the many British wounded, Rey generously allowed his soldiers to leave their defenses and rescue them. The onset of the Battle of the Pyrenees that day caused Wellington to order Graham to abandon the siege. As the Allies withdrew their siege guns, Rey launched a surprise sortie that inflicted 200 more casualties and seized some equipment. Shaken by their setbacks, Allied morale dropped and desertion became a problem.