By October 14, the trenches were within 150 yards (140 m) of redoubts #9 and #10. Washington ordered that all guns within range begin blasting the redoubts in order to weaken them for the coming assault. Redoubt 10 was near the river and held only 70 men, while redoubt 9 was a quarter of a mile inland, and was held by 120 British and Germans. Both redoubts were heavily fortified with rows of abatis surrounding them along with muddy ditches which surrounded the redoubts at a distance of about 25 yards. Washington devised a plan in which the French would launch a diversionary attack on the Fusiliers redoubt, and then a half an hour later, the French would assault redoubt 9 and the Americans redoubt 10. Redoubt 9 would be assaulted by 400 French Regular soldiers under the command of Lieutenant Colonel Count William Deux-Ponts and redoubt 10 would be assaulted by 400 troops under the command of Alexander Hamilton. There was briefly a dispute as to who should lead the attack on redoubt #10, Lafayette named his aide, the Chevalier de Gimat, to lead the attack, but Hamilton protested, saying that he was the senior officer. Washington concurred with Hamilton and gave him command of the attack.
At 6:30 pm, gunfire announced the diversionary attack on the Fusiliers redoubt. At other places in the line, movements were made as if preparing for an assault on Yorktown itself, which caused the British to panic. With bayonets fixed, the Americans marched towards redoubt #10. Hamilton sent John Laurens around to the rear of the redoubt to prevent the British from escaping. The Americans reached the redoubt and began chopping through the British wooden defenses with their axes. A British sentry called a challenge, and then fired at the Americans. The Americans responded by charging with their bayonets towards the redoubt. They hacked through the abatis, crossed a ditch and climbed the parapet into the redoubt. The Americans forced their way into the redoubt falling into giant shell holes from the bombardment of the redoubts. The British fire was heavy, but the Americans overwhelmed them. Someone in the front shouted "Rush on boys! The fort's ours!" The British threw hand grenades at the Americans with little effect. Men in the trench stood on the shoulders of their comrades to climb into the redoubt. The bayonet fight cleared the British out of the redoubt and almost the entire garrison was captured, including the commander of the redoubt, Major Campbell. In the assault, the Americans lost 9 dead and 25 wounded.
The French assault began at the same time, but they were halted by the abatis which was undamaged by the artillery fire. The French began to hack at the abatis and a Hessian sentry came out and asked who was there. When there was no response, the sentry opened fire as did other Hessians on the parapet. the French soldiers fired back, and then charged the redoubt. The Germans charged the Frenchmen climbing over the walls but the French fired a volley, driving them back. The Germans then took a defensive position behind some barrels, but when the French prepared a bayonet charge, the Hessians threw down their arms and surrendered.
With the capture of redoubts 9 and 10, Washington was able to have his artillery shell the town from three directions and the allies moved some of their artillery into the redoubts. On the October 15, Cornwallis turned all of his guns onto the nearest allied position. He then ordered a storming party of 350 British troops under the command of Colonel Robert Abercromby to attack the allied lines in order to spike the American and French cannons. The allies were sleeping and unprepared. As the British charged, Abercromby shouted "Push on my brave boys, and skin the bastards!" The British party spiked several cannons in the parallel and then spiked the guns on an unfinished redoubt. However, a French party came and drove them out of the allied lines and back to Yorktown. The British had been able to spike six guns, but by the morning they were all repaired. The bombardment resumed, with the American and French troops engaged in friendly competition to see who could do the most damage to the enemy defenses.
On the morning of October 16, more allied guns were in line and the fire intensified. In desperation, Cornwallis attempted to evacuate his troops across the York River to Gloucester Point. At Gloucester point the troops could break through the allied lines and escape into Virginia and then march to New York. One wave of boats made it across, but when they returned to take more soldiers across, a squall hit, making the evacuation impossible.