What are the most significant and memorable events or dates of a military career?

I'd say being selected for MSG this year has been the most memorable and important achievement of my military career. It is extremely difficult to make MSG in my CMF and knowing I made the cut validated many years of hard work and being a team player.

There two really significant dates to me: Nov 10, 1966, when I entered ACDU and Sep 30, 1966, when I retired. Along the way, There were some other important dates in my career: October 3, 1976; I was married to the love of my life; I was selected for, initiated, and promoted to CPO; I attended the Senior Enlisted Academy (Class 09, Green); I was promoted to Master Chief and selected as Command Master Chief!; I built and then Commissioned USS Anzio (CG-68) in Norfolk VA on May 2, 1992.

Day I went in
Days while in too numerous to single out
Day I got out

All the above. Also marrying and the arrival of my daughter and son.

Probably a toss up between the day I commissioned and my father who was in the Air Force was there for the ceremony and receiving my first challenge coin in front of formation for outstanding work during AT.