I was looking it this list of wars involving England and noticed that there was often 25 years or more between major wars. Would lesser vassals have fought each other? Or would soldiers go long periods of time without fighting? This goes against what I used to think of the Middle Ages - as a time of constant warfare and violence.
I only mentioned England but I’m interested in other European countries as well.
In the case of what we know today as Spain there have been a number of small scale conflicts between different feudal lords in the High/Late Middle Ages, some better known than others.
The wars in Biscay called Guerras Banderizas were wars between two main nobiliary factions (oñacinos and gamboínos) that lasted for decades. There were based more or less on chevauchées and other such actions, and eventually involved just about all of the relevant noble families of the region.
In the last decades of the 15th century there was a long war between the duke of Medina Sidonia and the marquess of Cádiz (Rodrigo Ponce de León) for the possession of the almadrabas of Cádiz and Rota, that ended with the peace agreement between them signed in 1472.
Gonzalo Fernández de Oviedo, in his Batallas y Quinquagenas, frequently talks on the wars and conflicts between different noblemen, and gives a particular report on the case of Juan Núñez de Prado and the wars against his enemies.
During the time of Henry IV of Castile, there were many small wars between noblemen, or even nobles against the church, forcing the crown to intervene in more than one instance, as was the case when Isabel the Catholic came to the throne.
In Galicia, Pedro Pardo de Cela had usurped a couple of fortresses from the blishop of Mondoñedo, and finally entrenched himself in the tower of Frouseira. Eventually, the Queen's justice intervened manu militari to put an end to this, finally capturing Pedro Pardo and executing him for treason as he failed to comply with the Queen's direct orders of him surrendering his fortress to the bishop of Mondoñedo. Worse thing is that Pedro Pardo was not an isolated case: Pedro Álvarez de Soutomaior was constantly at war against the count of Ribadavia, the Moscosos were frequently at war with the Pardos, the Lanzós against the Andrades. In the words of Jerónimo Zurita, chronicler, "estaban los nobles muy arriscados unos contra otros" (the lords were very entrenched ones against the others). They would even profit from the civil wars of Castile or other wars to wage their particular feuds, as the famous case of Pedro Madruga usurping the village of Tuy and taking the bishop as hostage, or taking a son of the Count-Duke of Benavente hostage during the castilian civil war of 1474-79, in which he sided with the king of Portugal.