Why was there tension between france and germany in the early 1900s? ?

From the end of the Thirty Years War in 1648 to the end of the Napoleonic Wars in 1815, France had been the master of Europe. The 18th and 19th centuries, however, were not kind to France. French decline began in the beginning of the 18th century after losing a series of wars to Britain (Spanish Succession, Austrian Succession, Seven Years’ War). Even the war it technically won, the Revolutionary War, left France worse off than before. The Revolutionary Wars had reversed French decline somewhat. But the Napoleonic Wars, while it took France to dizzying heights unseen since the days of Charlemagne, left France exhausted, eventually defeated, and broken.