Holy Guardian Angel Feast Day - 2 October

Quoted from Catholic Daily Readings [1]:

The memorial of the Holy Guardian Angels is an obligatory memorial of the Catholic Church. It is celebrated on October 2 every year in the Catholic Church. The memorial dates back as early as the 4th century when it was first observed by the Franciscan order in 1500 AD.

This memorial began as a local feast celebration but thereafter, in 1607, Pope Paul V released the papal decree that placed it in the General Roman Calendar.

Quoted from Catholic News Agency [2]:

The prayer to the guardian angels has been present in the Church since at least the beginning of the 12th century:

Angel of God,

my Guardian dear,

to whom His love

commits me here,

ever this day

be at my side,

to light and guard,

to rule and guide.

Amen.

[1] https://catholicreadings.org/holy-guardian-angels/, quoted without hyperlink.

[2] https://www.catholicnewsagency.com/saint/the-guardian-angels-612