NELSON COUNTY, Va. (CBS19 NEWS) -- Thomas Nelson is a veteran making sure other veterans aren't forgotten.

"If you don't, we're going to just fall in a trap and just not honor the people that served us," he said.

He comes from a long line of people who served their country.

His fourth great-grandfather is another Thomas Nelson, the namesake of Nelson County and a signer of the Declaration of Independence. 

Nelson himself served in Vietnam, and in his retirement, he's mapping veterans' graves throughout the county.

"I enjoy it because it helps families. People want to know about their families and I’m willing to help," he said.

After working in the Navy and civil intelligence, he's good at it too.

"Oak Hill Baptist church, I thought there were 35 there, it's up to 56 now. And, some of them are in pretty bad shape and all that and you have to decipher what you see," he said.

Nelson has input more than 20,000 graves online and completely mapped out seven cemeteries. One of those cemeteries is Jonesboro Cemetery, where he and the American Legion Post 17 have marked 303 veterans' graves with American flags for Memorial Day.

"Some of them gave their life. To remember their service and what they did for our country. A lot of them you don't know the details of their service, but it's so important to know who has protected us all these couple hundred years," he said.

He doesn’t always help find people's ancestors. One grave he put online was of a soldier killed in Vietnam. Fifty years later, the soldier who escorted his body home found the posting and came to pay his respects one more time.

"It was pouring down rain. The time we went and started our service here, all the clouds went away. So that was the Lord working his ways," Nelson said.

He said his goal is to make sure veterans and Memorial Day are honored the right way.

"It's not a mattress holiday. It's a Memorial Day for those who have served the country in this way," he said.

On Memorial Day, Nelson and American Legion Post 17 will visit each of the seven cemeteries they marked and host small ceremonies throughout the day.