On October 12, the attack on Paris began. From all sides, American troops, accompanied by a short and sharp artillery bombardment and air strikes from A-20 bombers, began to break through Choltitz's outer line of defenses. Thanks to information on German positions from the FFI, the Americans were able to bring up artillery and specifically target hidden German strongpoints. By the evening of the first day, the brittle German line fragmented. Occasionally, die-hards stood and fought to the death, but by and large, the hungry Germans surrendered after fighting for several hours. At the time that the battle for Paris began, Choltitz still had 33,000 soldiers and 84 tanks remaining to the defense. The Allies had upwards of 50,000 men involved in the battle, with additional reinforcements available had the commander of the attack, General Joseph Lawton Collins, requested them. Because the American force was so ably assisted by FFI partisans, who numbered at least 20,000, he felt no need to do so. He did, however, avail himself regularly of Allied air support available to the Corps involved in Paris. Collins had been commander of VII Corps in the First Army, and was widely considered the best corps commander in the U.S. Army at the time. For this reason, he was assigned command of the Corps assigned to liberate Paris.
By October 15, the second line of defenses, the one organized around the ring of boulevards surrounding the central portion of Paris, was fully invested. Here, the assistance of the FFI was less useful, primarily because Choltitz's garrison had mostly cleared the region inside the loop of partisans. Occasionally, FFI fighters were able to show the Allies a weakness in the German defense, but after this point, the attack became a street-by-street slog. Collins had resolved at the start of the attack to be "deliberate and careful not to waste the resources allotted me." This meant that whenever a German strongpoint was encountered, the Americans would bring up artillery and fire directly into the strongpoint, rather than attempt to immediately attack with infantry. The GMC M3 halftrack-mounted 75mm gun was used with great effect in this way. In addition, Allied tankers found — as had the Germans two months earlier — that armor-piercing ammunition was the best way to penetrate the thick stone walls of many older French buildings. In many ways, the fighting in Paris was similar to that occurring simultaneously in the German city of Aachen, two hundred miles to the north. There, as at Paris, Hitler had ordered the city held at all costs. Both cities had immense historical value, both were defended by "true Nazi" commanders, and both cities featured fierce street-by-street fighting.
No account given here of the fighting of this period can do it justice. A reader can best call up descriptions of the fighting in Stalingrad or read Albert LeDoux's "Liberation Delayed" for an excellent account of these days. Rubble-strewn streets, destroyed buildings, and snipers abounded for both sides. American infantrymen learned to hate the tough stone of older French buildings, as it was all but impervious to small arms fire, and almost by law, seemed to hold a German squad that had to be rooted out before the advance could continue. But continue it did, by dint of hard effort and relentless Allied pressure. By October 23, Choltitz's position was becoming increasingly untenable. Ammunition, never plentiful with the drain forced by fighting partisans, was becoming critical. In addition, several stockpiles of food had fallen into American hands, and German soldiers, hungry and desperate, were beginning to surrender en masse. Their morale, never strong in the midst of a surrounded and besieged city, had fractured badly when the Americans attacked. Fully one in three surrendered before Choltitz himself did on November 11, 1944.
The day before the surrender, the central bastion was ablaze with explosions as the Germans destroyed anything of value. As a final coup de gras, the Germans destroyed the city's waterworks, which had been supplying the defenders with water from the rubble-choked banks of the Seine throughout the battle. So much rubble had been dropped into that most French of rivers that in many places wreckaged formed dams, causing the river's water to rise above its banks, flooding the surrounding streets before the dams washed away, only to reform further downstream, where another pile of rubble waited. Alone amid the chaos, Notre Dame survived. Though damaged by shelling and American bombing, it still stood when Choltitz sent a messenger bearing a white flag to General Collins. American forces had not yet penetrated the central bastion, but fighting was taking place a half a dozen blocks from Choltitz's headquarters in the basement of the Hotel Meurice. When Choltitz surrendered, he had just 8,000 men still fighting. 14,000 had been killed, and 11,000 had already surrendered to American or French forces. American casualties were lighter, but still high. 8,329 American soldiers were killed in the liberation of Paris, and French casualties are estimated to have been higher than those of the Germans. Including the period of the uprising prior to October 12, it is estimated that upwards of 80,000 French men and women were killed directly resisting the Germans in Paris. This does not include the tens of thousands of civilians believed to have died due to malnutrition, disease or fighting in the embattled city. Much of the central portion of Paris lay in ruins, and virtually all public buildings and structures used as defensive strongpoints were either destroyed or damaged to the point that they had to be torn down. Despite the high cost, Paris had at last been liberated.