Transcription: The medieval fortifications worked very well against armies that were armed with swords, spears, arrows, and even catapults. However, toward the end of the medieval era, gunpowder and cannon were invented. These inventions made almost all fortifications at that time obsolete. Consequently, a new concept in fortification was needed and developed. Using filled angled walls, which would still be too steep to scale easily, it was discovered that fortresses would not crumble under cannon shot. Angled walls can still be seen in many modern military designs. you
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