Which ceremoney at Vijay Chowk on January 29 officially denotes the end of Republic Day festivities?

After three days of Republic Day parade, a moving ceremony known as “Beating Retreat” is held at the Vijay Chowk in New Delhi. This ceremony revives an ancient war custom according to which troops used to stop fighting at sunset. Bugles announcing the sunset would sound in the battlefield. As soon as soldiers heard these bugles they would stand still in the battlefield and war would be stopped for the day.