Maghi commemorates the Chali Mukte, the "Forty Liberated Ones", forty Sikhs who had earlier deserted Guru Gobind Singh but returned to die fighting for him at the battle of Muktsar in 1705, and were, by tradition, granted liberation (mukti) by the Guru, who tore up their letter of desertion; the town took the name Muktsar, "the pool of liberation", from the event. The festival is kept on the first day of the month of Magh (around 14 January), the day after the winter solar festival of Lohri, and it falls on Makar Sankranti, the sun's northward turn, so that a pan-Indian solar festival is given a specifically Sikh meaning.
The principal observance is at Muktsar itself, where a large fair and pilgrimage gather at the tank associated with the battle, with bathing, continuous readings of the Guru Granth Sahib, kirtan and langar; gurdwaras everywhere hold services and free community meals. Maghi honours the forty who redeemed their earlier failure through sacrifice and loyalty, and the day's teaching turns on the possibility of return and redemption, the deserters becoming, in the tradition, the model of those who give everything for the Guru. It is one of the fixed points of the Sikh calendar tied to the solar rather than the lunar reckoning.