Robin Williams was big on performing for the troops. Through the USO he visited Kuwait, Afghanistan, and he was in Iraq as well.
You probably saw this video of him in Kuwait when “Retreat” (“Colors” to swabbies and Marines) sounded as the flag was lowered at the end of the day.
Here, in two parts, is a complete performance, Robin Williams performing for the troops at Kandahar Airbase in 2007, in two parts:
And this tweet from the Motion Picture Academy says it all:
Best tribute, though, was from my daughter: