In the first place, the numbers of the fighters on either side was small--ridiculously small, we may think. The total population of the countries was nothing like as dense as it is now. But even in proportion to that lesser population, the fighting forces were small. In the recent Great War we saw "nations in arms," as has been truly said. Every man who could possibly be spared from the peace work that had to be continued if people were to have food to eat and other bare necessities of life, was pressed into the fighting. In those older wars only a very few of the population fought. The rest might go on with their ordinary work, for the most part of an agricultural kind, so long as their land was lucky enough not to be the scene of the fighting. And the troops moved slowly, so that the campaign was restricted to comparatively small spaces. In the winter there was little or no fighting. The soldiers went into "winter quarters." Probably this was largely because the roads were so bad and the country was so undrained and marshy, that it was almost impossible for them to move about with any artillery and baggage horses. Generally they went into the towns for their winter quarters. And if these towns had walls round them, as in those days many had, they were tolerably secure within the walls, so long as they had collected enough provisions, because there was no artillery powerful enough to batter down a strongly built wall. Doubtless the misery caused by the perpetual fighting, and the coming and going of armies during so many years, was very great, even so. It is said that in the principal areas ravaged by the war the population {77} was reduced to one-third of what it had been before. But a consideration of the leisurely way in which the fighting was conducted, and the small number engaged in it, helps us to realise how the people of the countries were able to endure it at all. It also helps us to understand how it was that it took so long to bring the war to a conclusion. The Protestant King of Denmark took the lead of the Union at the beginning of the long struggle, and at first the Protestants suffered many defeats. The great leader of the Catholics, Wallenstein, overran Denmark itself. The outlook for the Protestant cause was as black as it well could be. At this darkest moment Gustavus Adolphus came with his Swedes from the north, and the Catholics were driven back. Within a few years he was invading Germany, and in 1632 he fought the very important battle of Lutzen, in which the Protestant forces were completely victorious. But it was a victory dearly bought, for Gustavus himself was killed in the battle and the Protestant cause found no other leader of equal ability.