h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

It is perhaps worth noting that the Merovangian decline began fairly early on in their history when the nobles reversed the appointment of the Mayor of the Palace.

This title was at first semi-honorary, the nobles holding ceremonial, servant-like, positions in the palace, such as cup-holder. The Mayor was most significant, being effectively chief servant, overseeing the running of the Palace and its affairs. This significance led to him being the king's liason officer with the nobles.

When, exploiting a disputed succession between minorities, aggravated by the tendency to divide the lands between a king's heirs (Neustria and Austrasia being the main divisions), the nobles appointed the Mayor instead, he became their liason officer with the crown. As the crown ran out of awards to keep the nobles loyal they grew in power and the Mayor grew in power with them (helped by being dynastic estate manager).

The post became unofficially heriditary in the ancestors of the Carolingians. One of these, Pepin of Heristal, achieved in battle the union of the Merovangian lands and, in so doing, secured for himself the title Dux et Princeps Francorum -- his time in the post being recorded on all documents of state like that of the king. This was the begining of the era of les Rois Feinants.

The Mayors deposed and replaced kings at will and for a time Pepin's son, Charles Martel, didn't bother to appoint one at all. He was the father of Pepin the Short who finally ended Merovangian royalty with the deposition of Childeric the Stupid.

Sorry, that went on a lot longer than I thought it would. The original article was great.