|Æthelred II (the 'Unready')|
Land granted by the king was known as ‘bookland’ and was absolved from all service with the exception of three. According to a grant by King Edgar (959-975)  those three things were: fixed military service, the restoration of bridges, and of fortresses. A grant by Æthelred II (979-1016)  calls for national military service, the construction of fortresses and the restoration of bridges. The Thegn’s law  tells us that:
“He be entitled to his book right, and that he shall contribute three things in respect of his land: armed service, and the repairing of fortresses and work upon bridges. Also in respect of many estates further services arise on the king’s order, … equipping a guardship, and guarding the coast, and guarding the lord, and military watch …”
The king was prepared to grant away rights privileges but not, it seems, his right to military service. The exact nature of the service is not stipulated, but it must have been important. Archbishop Wulfstan and Ælfric the Homilist divided Anglo-Saxon society into three orders: those who fight, those who labour, and those who pray. Does this mean that the aristocracy was a warrior class? The nobility was required to provide military equipment  and there can be no doubt that a substantial part of their service was of a military nature.
|A charter of King Æthelred II|
Just as the heriot (war gear) varied according to rank, so the military service requirement differed for men of varying resources. The king had at his disposal his household troops.* Mercenaries were employed, (the career of Thorkell the Tall is evidence of this) but in essence the composition of the fyrd was based on a territorial levy. The requirement was for one man from every five hides of land. Service was basically for sixty days, in a system of rotation, but only in times of war. The Anglo-Saxon Chronicle entry for 920 tells us that “when this division of the English levies went home, the other came out on military service and occupied the fortress at Huntington.”  A landowner with more than five hides of land would be responsible for providing the requisite number of men.
A fine was payable for neglect of military service, and this ‘fyrd-wite’ was set at around forty shillings per man. Commutation, a payment in lieu of service, was lower, at around twenty shillings per obligation. A thegn liable to service could have his lands confiscated if he defaulted.  This did not necessarily mean that a thegn had to fight. He could send the required number of men without going himself; he would still be fulfilling his obligation.
Mention is made of two types of fyrd (army), the select fyrd and the great fyrd. The distinction between the two might have been thus: the select fyrd consisted of soldiers who fought in battle, and the great fyrd may have been the back-up, repairing bridges and fortresses. 
The expensive equipment of the ealdormen, king’s thegns and the lesser thegns would have set the aristocracy apart from the ordinary fighting ceorl. The poem, The Battle of Maldon, describes the ornate trappings of a nobleman in battle:
“An armed man then went to the Earl,
Wanting to strip him of his armbands, armour,
Ring-mail and ornate sword.”
|The battlefield from the air - Terry Joyce|
terry joyce / Northey Island / CC BY-SA 2.0
Clearly the nobility who fought did so with expensive war gear, but to fight was not their only obligation. As landlords, they were responsible for the organisation, summoning and assembling of the fighting forces. They were also involved in the essential organisation to ensure that competent levies turned out to perform military duties on behalf of their estates.
The military crisis precipitated by the resumption of Danish raiding served to place emphasis on the fighting role of the thegn. But was the aristocracy a warrior class?
Their military equipment set them apart in wealth and status from the rank and file, and their bookland was held from the king immune from all except military service. Yet if this was a warrior aristocracy one would expect to see them holding their land as a reward for military service, and their status deriving from their military rank. This was clearly not the case; that land was not held as reward for military service is a major stumbling block for any historian trying to prove that pre-Conquest England was feudal.
Land was granted for many reasons. King Æthelred II granted Æthelwig land because he did not wish to sadden him.  Apart from his being a servant of the king there seems to be no other reason for the grant. A ceorl could amass all the weapons of a thegn and still remain a ceorl if he did not possess five hides of land.  Land remained the source of wealth and the indicator of status. Military service was an important part of a nobleman’s duties but, as we have seen, it was only one of many.  One might also expect that in times of peace less emphasis would be placed on the thegn as a warrior than in times of war.
*During the time of Cnut, the household troops were referred to as housecarls. Cnut’s reign was not in the tenth-century, though, and Nicholas Hooper’s article  provides, for me, compelling argument to suggest that the housecarl differed little from the English thegn.
 Grant by King Edgar to his thegn Ælfwold 969 EHD (English historical Documents) 113 p519
 Grant by King Æthelred to his thegn Æthelwig 992-995 EHD 117 p525
 Origins of English Feudalism 61 p145 “The Rights and Ranks of People”
 For more on this, see my article on Defining the Nobility in Later Anglo-Saxon England
 Anglo-Saxon Chronicle (A) 921 (920)
 This point is discussed by DJV Fisher in the Anglo-Saxon Age Ch13
 See Warren Hollister, Anglo-Saxon Institutions. There is also a possibility that the Select fyrd served locally, and that the Great fyrd was the national army
 EHD 117 p525
 See HR Loyn The Governance of Anglo-Saxon England p167
 See last times’s article on duties and responsibilities HERE
 The Housecarls in England in the Eleventh Century - N Hooper
(Above illustrations - public domain unless otherwise accredited)