Sentence:  Bailly , after leaving Fort Snelling in <WSD>August</WSD> 1821 , was forced to leave some of the cattle at the Hudson's Bay Company's post on Lake Traverse `` in the Sieux Country '' and reached Fort Garry , as the Selkirk Hudson's Bay Company center was now called , late in the fall . 
Meaning of the word marked with <WSD> tags:  the month following July and preceding September