The Sikhs vacated the premises as a storm brewed leaving the fort in pitch darkness, the enemy forgetting all about the oaths they had taken attacked the Sikhs. With the enemy hot on their heels the Sikhs reached the river Sarsa running near to Anandpur Sahib, which had swollen due to the storm and winter rains. The hungry and weak army of the Sikhs had a difficult crossing to make in the wake of the sea of Muslim and ungrateful Hindu army behind them. It was a tragic scene of devastation. The Guru was separated from the Sikhs as well as from his family. The whole Sikh army was scattered in the dark as small groups moved to safety in any direction they found. Facing all these unfavorable conditions, Sikhs were to make unaccountable sacrifices
The Guru along with forty of his followers crossed the river and arrived at a small clearing, they took shelter in an unsound small fort called 'Kachhi Garhi’ at Chamkaur. The enemy soon arrived and laid siege. This Gharhi was surrounded by 10 lakh soldiers of the enemy. No band of soldiers have ever faced such unfavorable odds, not even the Spartans. This was not narrow a passage to defend, this was a small shakey havali surrounded on all sides by the enemy baying for blood.
The two Sahibzadas - Baba Ajit Singh and Baba Jujhar Singh - and three other archers took up positions, along with Guru Gobind Singh Ji in the upper portion of the house. Eight persons each were deputed to guard each of the four sides. Two expert swordsmen -Bhai Madan Singh and Bhai Kotha Singh - stood to guard the only entrance to the haveli.
The arrows from upper storey of the haveli kept many a soldier at bay. Those who came forward to storm the garhi, met piercing arrows. They either perished or preferred to pull back, or faced hand-to-hand fights with Singhs guarding the four sides. Faujdar Nahar Khan was one of those who fell to the arrows of Guru Gobind Singh himself. The onslaught continued relentlessly as the enemy continually attacked all sides of the gahri.
The battle lasted all day. When the ammunition and arrows in the garhi almost ran out, the Singhs came out in batches of five, with swords and spears in their hands, to face the enemy that far outnumbered them. Their determination and fighting skill helped them kill many of the enemy, but odds were so heavy against them that they all fell in the field, one by one. They were followed by the next batch of five, charged with emotions of fighting a treacherous enemy. Determined to fight with all their vigor, they too were to lay their lives the same way.
The two elder sons of Guru Ji - Baba Ajit Singh (17 years old) and Baba Jujhar Singh (15 years old) stepped forward and volunteered to go fight the hordes outside. The Great Guru was greatly impressed and prepared them himself for battle before sending them out to the field of battle to sacrifice their lives. Included in this band were three of the original Panj Piyaray (Five Beloved ones) Bhai Mohkam Singh, Bhai Himmat Singh and Bhai Sahib Singh.
Each Sikh went into battle with such ferocity, like a hungry lion scattering its prey that it unnerved the enemy, but the hordes overwhelmed them and they fought to the last breath. Such heroics have seldom been seen before or since. This situation brought true the prophecy of one of Guru Sahib Ji’s compositions :
"Call me Gobind Singh, only, when each of my Sikh will fight with more than one and a quarter lakh of enemy."
By the nightfall, only six persons - Guru Gobind Singh Ji, two of the " Beloved Five" (Bhai Daya Singh and Bhai Dharam Singh), Bhai Sant Singh, Bhai Man Singh and Sangat Singh remained alive in the garhi. The Singhs decided that Guru Gobind Singh must leave the haveli, so that he could rally his followers again. If he perished, loss to the community would be irreparable. Guru Ji wanted to face the enemy but the five Sikhs in the form of Panj Piyaray said that Guru Ji must do as they say, to which Guru Sahib Ji relented.
It was proposed that Guru Sahib Ji should change his attire with Sangat Singh, who somewhat resembled him in stature. By his being visible, the others might get enough time to reach a somewhat safe distance. Reluctantly, the Guru agreed, to the propsal, which the Singhs presented as the matta of five, which was binding. . Bhai Sant Singh decided to stay back to guard the entrance, and thus gain some additional time, when the enemy barges in.
In the middle of the night Guru Gobind Singh and three remaining Sikhs - Bhai Daya Singh, Bhai Mohkam Singh and Bhai Man Singh - left the haveli, with a plan to go in different directions but meet in a garden outside Machhivara. Even at this critical moment Guru Ji was fearless and full of valor, clapping loudly three times and shouting “here goes the Guru of the Sikhs, face me now if you have the courage” and set off into the enemy hordes. Fighting their way through the enemy ranks Guru Ji made it out and headed towards Machiwara.
This whole incident is referred to in the historical document called Zafarnama, penned by Guru Gobind Singh himself. Notice that the figure of 10 Lakh enemy is refered to by Guru Sahib Ji giving more credence to this figure rather then it being a generic value. Also, it does not seem implausible for the emperor of India to be able to muster a million men as his earlier attempts with well documented fewer numbers had failed even though they had still had overwhelming numerical advantage. In addition, the time disparity also gives the chamkaur battle more credibility in that it is something from recent history (~300 years) whereas the battle of Thermopilae is said to have occurred over 3000 years ago.