David Cronon, age 15, of Columbia, Tenn., for his question:

WHAT CAUSED THE THIRTY YEARS' WAR?

The Thirty Years' War, which continued from 1618 until 1648, was caused by the deep seated hostility between the German Protestants and the German Catholics. The two groups disagreed in their interpretation of the Peace of Augsburg which had been intended as a settlement of the religious question in Germany.

The fight started as a civil war in the German states. Before it was over, most of the nations of Europe were involved, and the war had become a general struggle for territory and political power.

For years people suffered misery and hardships because of the war. Many were killed.

Those who survived saw ruin everywhere with whole cities and villages destroyed. Art, science, trade and industry declined. It took almost 200 years for Germany to recover.