Date added: 9 Jun 2015
The standard was a usually a flag that sometimes had a golden icon on the top. A very famous example of this is the iconic French standard of a gold eagle and the French flag. Each regiment would have its own standard that was carried by the standard bearer and it would be the regiment's job to protect him. Both sides would try to capture the enemy's flag and kill the standard bearer to show they were defeated. Although they would be defended by their own side, they would have been a target for the enemy.
As the standard was so large, it would have been rallied round by soldiers to gather together and form a strong position. It would have also meant that officers could easily locate the centre of their regiment. The standard bearer would not have done a lot of fighting but would be in the middle of the square formation. If the regiment had been destroyed and the standard bearer survived, it would be his duty to escape and return the standard back to another British regiment or stronghold.
If you click on the image, the standards that I've selected are (from left to right) the Prussian standard, the British standard and the French standard, all of which served at Waterloo.