The flag.
This is the uniform of a soldier in the (I believe) 1st Grenadier Regiment during the battle of Waterloo, which would happen from June 15th, 1815 to July 8th, 1815. Also shown in the background is the uniforms of Napoleons artillery men, the background used for reference was the made in 1970 epic film ¨Waterloo¨. With the Fort Hougoumont, on the left side. Where Napoleon would order his army to begin the attack at exactly 11:35 A.M.