1. William was able to gain Papal support for his invasion, claiming that he would support and promote the wishes of the Catholic church in England when he became king. If the Pope gave his blessing for a war then, as God’s messenger on earth, this would be a chance to do God’s work…and potentially get rewarded for it too.
William was attempting a cross-channel invasion - no easy task – and he would have to work hard to gain the support he needed for such a risky campaign.
William had no standing navy, he would need to raise both a navy and an army to successfully invade England.
William’s army made use of cavalry. It is incredibly difficult to transport large numbers of horses and keep them fed.
If William were successful then he would have conquered a relatively large piece of fertile and wealthy land. He would be able to reward people who fought for him by granting them land in England.
William would be able to get around some of the problems of supply by stealing and plundering resources when he landed in England.

2. Godwinson would be unable to have his soldiers ‘live of the land’ which is essentially steal and plunder. He would have to supply his army as he was fighting on land owned by people he was trying to protect.
Godwinson faced invasion from two potential enemies. He could not know when they would attack, nor where they would attack.
Godwinson did not have to move, he would be fighting on home turf. He could rely on the efficient British system of calling people for military service based on hides of land owned.
Godwinson did not have to worry about building hundreds of ships to transport his army.
If Godwinson emerged victorious in 1066 he could promise his men that they could retain their lands but could not promise them new lands, unlike Harald or William.

3. Hardrada would lead a nation of warriors in a campaign that Viking kings had carried out successfully for centuries. Furthermore, it could be argued that Hardrada himself was one of the most successful Viking warriors of all time.
Hardrada could muster a fleet of 300 longboats and thousands of troops relatively easily. The Vikings were used to fighting campaigns across the sea.
Hardrada could expect some support from certain sections of the population, and he had the backing of Tostig, a man who knew England well and might help him gather more support.
Due to the organisation of the military under Edward, Godwinson was able to call up a navy during the year of crisis to serve.
If Harald were successful then he would have conquered a relatively large piece of fertile and wealthy land. He would be able to reward people who fought for him by granting them land in England.