The end of the Middle Ages saw the construction of larger, more powerful cannon, as well as their spread throughout the world. As they were not effective at breaching the newer fortifications resulting from the development of cannon, siege engines—such as siege towers and trebuchets—became less widely used. However, wooden "battery-towers" took on a similar role as siege towers in the gunpowder age—such as that used at Siege of Kazan in 1552, which could hold ten large-calibre cannon, in addition to 50 lighter pieces. Another notable effect of cannon on warfare during this period was the change in conventional fortifications. Niccolò Machiavelli wrote, "There is no wall, whatever its thickness that artillery will not destroy in only a few days." Although castles were not immediately made obsolete by cannon, their use and importance on the battlefield rapidly declined. Instead of majestic towers and merlons, the walls of new fortresses were thick, angled, and sloped, while towers became low and stout; increasing use was also made of earth and brick in breastworks and redoubts. These new defences became known as bastion forts, after their characteristic shape which attempted to force any advance towards it directly into the firing line of the guns. A few of these featured cannon batteries, such as the House of Tudor's Device Forts, in England. Bastion forts soon replaced castles in Europe, and, eventually, those in the Americas, as well.