Transcription: After the Medieval era, the square-walled perimeter of fortresses evolved into a more complicated polygon shape. With this design, any single wall was defensible from at least three other walls. Together with angled walls, the fortress would be defensible even against an army armed with cannon. A good example of this type of fortress was Fort Pitt, which was built during the early 1700s at the intersection of the Allegheny, Ohio, and Monongahela Rivers in Pennsylvania. The fortress was able to control river traffic, and therefore also the over a large section of the territory. The city of Pitt ...
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