The cannons roared in perfect synchrony, with the National Anthem saluting the President and the National flag, a feat they have been performing with incredible finesse for over five decades.
Each cannon is fired at an interval of around 2.25 seconds to encompass the entire length of the 52 seconds of the anthem in three successive rounds.
The artillery is maintained by the gunners of the elite 871 Field Regiment (SHINGO) and are kept at Delhi Cantonment.
The vintage artillery is brought out only on a few selected days including Independence Day, Republic Day and Martyrs' Day. The honour is also conferred to visiting Heads of States at the Rashtrapati Bhavan.
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"They are old British guns from the pre-Independence era passed on to us. The country now has modern defence ammunitions, so these guns have been preserved to be used for ceremonial functions. They are not capable of fighting war," the officer added.
The firing of the cannons are done in a controlled manner to maintain appropriate decibel levels.
"The propellant is loaded into the cannons and that is followed by the blank firing. The sound is produced due to the extreme pressure as the propellant burns and gases are produced," he said.
Interestingly, in pre-Independence India, the 21-gun salute was given to few selected rulers of princely states on the basis of prosperity rather than giving preference to military might.