[3] This was later altered to five years. One very real power was vested in the Reichstag. It had full control of the empire's purse strings. Bills for raising revenue and all measures making appropriations had to originate in this chamber, and its assent was required to their enactment. The reason for its failure to exercise this control resolutely must be sought in the history of the German people, in their inertia where active participation in governmental matters is concerned, and in those psychological characteristics which Bismarck so well comprehended and upon which he so confidently counted. No people on earth had had a more terrible or continuous struggle for existence than the various tribes that later amalgamated to form the nucleus for the German Empire. Their history is a record of almost continuous warfare, going back to the days of Julius Caesar. In the first years of the Christian era the Germans under Arminius (Hermann) crushed the Romans of Varus's legions in the Teutoburg Forest, and the land was racked by war up to most modern times. Most of its able-bodied men were exterminated during the Thirty Years War (1618-1648).[4] This almost constant preoccupation in war had a twofold result: it intensified the struggle for existence of the common man and kept him from devoting either his thoughts or energies to problems of government, and it strengthened the powers of a comparatively small ruling-class, who alone possessed any culture and education and whose efforts were naturally directed to keeping their serfs in the subjection of ignorance. These conditions prevailed until well into the last century. [4] The population of Germany dropped from twenty to less than seven millions during this war. The conditions can best be appreciated by a comparison with the conditions existing in England at the same time. England, too, had had her wars, but her soil was but rarely ravaged by foreign invaders, and never to the extent in which Germany repeatedly suffered. Parliamentary government of a sort had existed more than three centuries in England before it reached Germany. A milder climate than that of North Germany made the struggle for the bare necessaries of life less strenuous, and gave opportunity to a greater proportion of the people to consider other things than the mere securing of enough to eat and drink. They began to think politically centuries before political affairs ceased to rest entirely in the hands of the nobility of Germany.