One of the most important things to remember about early modern wars is that kings could not wage them on their own. They needed contribution of noblemen and wealthy townsmen. But from tonwsmen kings needed only money, nobles were indispensible for both money and personal service. In the dawn of the modern state without bureaucracy and military schools only nobles bred for warfare could provide officers. And we know that armies required more and more officers every decade as complexity of warfare grew along with Military Revolution. The custom was to fight as a family: fathers, sons, brothers, nephews and cousins campaigned together providing unequalled cohesion. Also, nobles brought to war their retinues, clients and mercenaries. Refusal of noblemen to enter the war meant that the war could not be waged with success or could not be started at all, as Christian IV of Denmark found out to his grief, twice.
Value of nobles to warring kings is obvious. But what was in war for them? Here is the best summary of the issue I ever saw, in quotes taken from different places of “War, State, and Society in England and the Netherlands 1477-1559” by Steven Gunn and David Grummitt (2007):
“The ability of noblemen to increase their own power through service to the prince in war was fundamental to the exchange of benefits between ruler and aristocrat, all the more so as war remained important to the self-image of noblemen and of the nobility as a caste. Contemporaries thought that noblemen liked war: the English ambassadors in the Netherlands reported in July 1521 that the nobles were preparing for war against France with as much joy as they would go to a wedding. Statistics suggest that they were heavily committed to it: in 1513 only one of the thirty-four fit adult English peers was not fighting the French or Scots or serving at sea.
War might increase noblemen’s political influence in at least four ways. Because noblemen were thought to understand war better than clerics or low-born admin-istrators, princes were expected, at least by Philip of Cleves, to listen to their advice more in wartime. Secondly, war necessitated the concession of control to individual noble captains and governors over considerable areas of the execution of policy and the allocation of government resources. Thirdly, great victories might win the prince’s gratitude and future trust for the man who brought them off. Lastly, the chance to campaign with the prince in person was the chance to gain his favour by conspicu-ous service and shared danger. The other side of the coin was that failure could bring humiliation and loss of influence. Sometimes the risks and costs of high command seemed just too great: thus Hendrik III of Nassau asked to be relieved of command in 1512 after two years’ campaigning against Guelders because his financial means were exhausted and he felt too inexperienced to continue the war.
Nobles built up clienteles or affinities to serve their purposes in local government and court politics as well as in war, but military service was often important in shaping these followings. The Howards’ experience suggests that nobles prominent as mili-tary commanders, office-holders, and local magnates developed different followings in these different capacities, but that these followings overlapped and might each support the lord in war. The creation of knights with royal permission was a particu-larly important means for noblemen to bind existing followers to them or to forge new allegiances. Knighting confirmed the lord’s role as a chivalric leader, recognizing the deeds of arms performed by those in his retinue, while increasing the status of the individual follower and binding the affinity together in a fellowship of arms”.