In the 17th Century precedence, also called rank or seniority, was an important aspect of running an army properly. First of all precedence solved the way in what order regiments should be ordering, whether this be on the parade ground, during a march or during a battle. In the latter situation, precedence gave an indication on the experience of the regiment (here the term seniority becomes clear). Usually the senior regiments were positioned on the flanks of the line of battle, with the junior regiments in the middle.
Secondly, precedence, in a way of determining ancienity of a regiment, was a means for regiments, that is its colonel, to claim right for survival when disbandments were announced after a war. Reversely, a more senior regiment may also have more chance of being re-formed in case of a new war.
Obviously, lack of clear precedence was sufficient reason to cause disputes between colonels over their respective seniority. (However, even with clear rules to set precedence, colonels could always find an argument to claim being more senior than the regiment listed one position higher .... )
In a series of posts the concept of precedence as it was regulated in the British Army between 1660 and 1715 will be detailed.