Since succeeding to the throne of England in 1272, Edward I had pursued an aggressive policy of expansion into the neighbouring kingdoms. He responded to a minor rebellion in Wales with a full-scale retaliation that went far beyond the original status quo, subduing the whole of the country to his rule. Several major castles were built to defend this new territory, including Caenarfon, Beaumaris and Harlech. The success of this campaign led Edward to attempt a similar conquest of Scotland. After the death of the Scottish king Alexander III, and that of his heir Margaret of Norway in 1290, the kingdom was left without an obvious heir. The two main competitors were John Balliol and Robert Bruce, but Edward I claimed the right to arbitrate b…
Editors. "English King, Edward I, conquers Scotland". The Literary Encyclopedia. First published 31 July 2012; last revised 30 November -1.
[http://www.litencyc.com/php/stopics.php?rec=true&UID=9349, accessed 26 April 2015.]