Who are these dressed in white?

I was at Fort Snelling last week for a burial at the National Cemetery.  The grounds are home to thousands of graves of military veterans over the last 140+ years, beginning with veterans who actually served at Fort Snelling when it was an active military post in the 1860s.  The officer who met us told us that they currently do nearly 5,000 burials a year there.

As I stood looking at those acres of grave markers I thought of this passage from St. John's Revelation:

"Then one of the elders addressed me, saying, "Who are these, robed in white, and where have they come from?'  I said to him, 'Sir, you are the one that knows.' Then he said to me, 'These are they who have come out of the great ordeal; they have washed their robes and made them white in the blood of the Lamb." (7:13-14)

As I thought about St. John's revelation I thought that perhaps the scene he saw was somewhat like the one in front of me - row after row of those dressed in white.  Will death have the last word?  Will the blood of the Lamb cover us all?  Who are these robed in white?