The Fourth Coalition against Napoleon's French Empire was defeated in a war spanning 1806–1807. Coalition partners included Prussia, Russia, Saxony, Sweden, and the United Kingdom.
Many members of the coalition had previously been fighting France as part of the Third Coalition, and there was no intervening period of general peace. In 1806, Prussia joined a renewed coalition, fearing the rise in French power after the defeat of Austria and establishment of the French-sponsored Confederation of the Rhine. Prussia and Russia mobilized for a fresh campaign, and Prussian troops massed in Saxony.