When King Alexander III ruled Scotland, his reign had seen a period of peace and economic stability. On 19 March 1286, however, Alexander died after falling from his horse. The heir to the throne was Alexander's granddaughter, Margaret, Maid of Norway. As she was still a child and in Norway, the Scottish lords set up a government of guardians. Margaret fell ill on the voyage to Scotland and died in Orkney on 26 September 1290. The lack of a clear heir led to a period known as the "Great Cause", with several families laying claim to the throne. With Scotland threatening to descend into civil war, King Edward I of England was invited in by the Scottish nobility to arbitrate. Before the process could begin, he insisted that all of the contenders recognise him as Lord Paramount of Scotland. In early November 1292, at a great feudal court held in the castle at Berwick-upon-Tweed, judgement was given in favour of John Balliol having the strongest claim in law. Edward proceeded to reverse the rulings of the Scottish Lords and even summoned King John Balliol to stand before the English court as a common plaintiff. John was a weak king, known as "Toom Tabard" or "Empty Coat". John renounced his homage in March 1296 and by the end of the month Edward stormed Berwick-upon-Tweed, sacking the then-Scottish border town. In April, the Scots were defeated at the Battle of Dunbar in East Lothian and by July, Edward had forced John to abdicate. Edward then instructed his officers to receive formal homage from some 1,800 Scottish nobles .
When they did not have a prominent leader, what did they say it was?
The lack of a clear heir led to a period known as the "Great Cause"