Size matters

Some basis for calculating the size of the armies

According to Frank McLynn in his book 1066, there are 4 types of longship 

Benches Oars Crew Notes
13 26 30  
15 30 32  
20 40 43 The most common
30 60 65  
In the calculations, the assumed ratio of these sizes is 2:2:5:1 or an average of 40 warriors (40.4) per longship

An estimate of 10,000 warriors and 2000 supporting personnel is sensible. This makes it bigger than the Norman forces at Hastings. 

As Riccall required a guard force, perhaps two thirds of the warriors were avaiable for the battle at Fulford.