Why Did Edgar Atheling Rebel?

Robert and his army of 900 men were massacred in Durham because the people of Northumbria did not want to have a Norman as their earl. Edgar Atheling joined the rebellion after the massacre at Durham and became the figurehead for the resistance.

Why did the Anglo Saxons rebel?

So because they thought they knew what a conquest felt like, like a Viking conquest, they didn't feel like they had been properly conquered by the Normans. And they kept rebelling from one year to the next for the first several years of William's reign in the hope of undoing the Norman conquest.

Why did Edgar Atheling not try for the throne?

Edgar Atheling had the strongest blood tie – but blood ties were not essential for the succession to the English throne at this time. All the claimants had some kind of family blood tie, except for Harald Hardrada.