Of the kings in whose reigns the Parliament gathered this mighty strength not one was likely to look with indifference on the growth of a rival authority, and the bulk of them were men who in other times would have roughly checked it.  What held their hand was the need of the Crown.  The century and a half that followed the gathering of the estates at Westminster was a time of almost continual war, and of the financial pressure that springs from war.  It was indeed war that had gathered them.  In calling his Parliament Edward the First sought mainly an effective means of procuring supplies for that policy of national consolidation which had triumphed in Wales and which seemed to be triumphing in Scotland.  But the triumph in Scotland soon proved a delusive one, and the strife brought wider strifes in its train.  When Edward wrung from Balliol an acknowledgement of his suzerainty he foresaw little of the war with France, the war with Spain, the quarrel with the Papacy, the upgrowth of social, of political, of religious revolution within England itself, of which that acknowledgement was to be the prelude.  But the thicker troubles gathered round England the more the royal treasury was drained, and now that arbitrary taxation was impossible the one means of filling it lay in a summons of the Houses.  The Crown was chained to the Parliament by a tie of absolute need.  From the first moment of parliamentary existence the life and power of the estates assembled at Westminster hung on the question of supplies.  So long as war went on no ruler could dispense with the grants which fed the war and which Parliament alone could afford.  But it was impossible to procure supplies save by redressing the grievances of which Parliament complained and by granting the powers which Parliament demanded.  It was in vain that king after king, conscious that war bound them to the Parliament, strove to rid themselves of the war.  So far was the ambition of our rulers from being the cause of the long struggle that, save in the one case of Henry the Fifth, the desperate effort of every ruler was to arrive at peace.  Forced as they were to fight, their restless diplomacy strove to draw from victory as from defeat a means of escape from the strife that was enslaving the Crown.  The royal Council, the royal favourites, were always on the side of peace.  But fortunately for English freedom peace was impossible.  The pride of the English people, the greed of France, foiled every attempt at accommodation.  The wisest ministers sacrificed themselves in vain.  King after king patched up truces which never grew into treaties, and concluded marriages which brought fresh discord instead of peace.  War went ceaselessly on, and with the march of war went on the ceaseless growth of the Parliament.

[Sidenote:  Robert Bruce]