My retirement

I joined the military at the age of 17 and served for four years. I wasn’t married during that time period. I married a year after leaving the military. Over the next 19 years, I’ve worked for a local government system. In 2005, I decided to use money in my 401K to purchase my military service credits to apply towards my retirement time in the local government system. I used 45K to purchase the credit. Since that 4 years of military time was prior to marriage, is the 45K considered marital property?

No, the retirement money you saved prior to marriage remains separate, regardless of the change in form.

Does this mean that even the appreciation on an asset an individual owns before marriage remains a non marital assets? For example, if an asset (401K, stock fund, etc) is worth $10,000 when someone is married, and has grown to $15,000 by the time of an ED, is the entire $15K exempt from ED or just the initial $10K?

The money saved prior to marriage is separate, as is the passive (market forces) increase in value. Contributions made after the date of marriage, and the growth thereon are divisible however.