"In the morning" vs "on the morning"?

In the morning we will go to the park.

On the morning of November 25th, where were you?

Used as a common time expression, "In the morning" is the correct phrase. E.g., I have many things to do in the morning. When using "on the morning", we might be referring to a specific morning, either future or past, and it is often followed by the preposition 'of'. E.g., On the morning of June 17th, we packed our bags and headed south. There may also be additional uses for both.