Castle building in England and Anglo-Norman Ireland was a deliberate part of a system of conquest, with castles built in specific areas to exert authority over a region as part of a larger campaign of central political authority. In contrast, in parts of the Holy Roman Empire, castles were part of the expression of factional allegiance, and in contested landscapes, castles could be built to directly oppose those belonging to other factions because political power was more broadly distributed. This can be seen in Germany's Altmühltal, where rival families built eight castles in ten miles along a river valley.
The official records of the city of London record that in May 1471, the mayor and aldermen of the city fortified the bank of the Thames to resist a large fleet which had appeared near the Tower of London. This was one of the most dramatic episodes of an eventful year, which saw Edward IV regain his throne after defeating his enemies at the battles of Barnet and Tewkesbury. The attack on London provides an opportunity to examine one of the few major sieges to occur during the Wars of the Roses and in particular the role of gunpowder artillery in determining the outcome
With the arrival of gunpowder in Europe in the 14th century, military practitioners were faced with a new challenge on the battlefield (though they initially tried to conceptualise the threat in old terms). They soon learned that gunpowder posed challenges for attacking the enemy as well as defending one's army or one's stronghold. This paper looks at this varied challenge through the lens of 'offense-defense theory', a product of modern political science and international relations, but rarely turned on much but the recent past. In particular this paper will look at the change in perception of what artillery was for in a siege situation and how both the attack and especially the defense changed in military strongholds in the late 15th through the 16th century.