Why is the ringing of bells an important custom of mexican independence day?

The ringing of bells in an important custom when Independence Day is celebrated in Mexico as it constitutes the manner of commemorating the so-called Cry of Dolores.

The Cry of Dolores was an event that took place in 1810 in the Mexican city of Dolores. A priest called Miguel Hidalgo y Costilla, after ringing the bell of his church, delivered the pronunciamiento. This is a term Spanish that is used to refer to a call to arms. Those bells and the subsequent pronunciamiento triggered the Mexican Independent War.

on november 6 and 7, 1917 (or october 24 and 25 on the julian calendar, which is why the event is often referred to as the october revolution), leftist revolutionaries led by bolshevik party leader vladimir lenin launched a nearly bloodless coup d'état against the duma's provisional government.