 Complete the following phrase:  From 1799 Yorck began to make a name for himself as commander of a light infantry Jäger regiment, being one of the first to give prominence to the training of skirmishers. In 1805, then with the rank of Oberst, he was appointed to the command of an infantry brigade as a vanguard force of the troops of Duke Karl August of Saxe-Weimar during the War of the Fourth Coalition. In the disastrous 