 Complete the following phrase:  Pétain led his brigade at the Battle of Guise 29 August 1914. At the end of August 1914 he was quickly promoted to brigadier-general and given command of the 6th Division in time for the First Battle of the Marne; little over a month later, in October 1914, he was promoted yet again and became XXXIII Corps commander. After leading his corps in the spring 1915 