The correct answer is: B: France. Great Britain started war with France in 1803, and it was one of so called Napoleonic Wars. This war was declared in may of 1803, because The British were increasingly angered by Napoleon's reordering of the international system in Western Europe, especially in Switzerland, Germany, Italy and the Netherlands. Britons felt insulted when Napoleon said it deserved no voice in European affairs (even though King George was an elector of the Holy Roman Empire), and ought to shut down the London newspapers that were vilifying Napoleon.
