Preparations for the invasion of England had been steadily proceeding, but Napoleon's aggressive demeanor after becoming emperor alarmed the European cabinets, so that Pitt was able to revive the coalition, and in 1805 Napoleon found himself at war with Russia and Austria, as well as with England. Forced by England's naval supremacy to abandon the notion of invasion, he suddenly changed front in August, 1805, and led his armies through Hanover and the smaller German states, disregarding the neutrality even of Prussia herself, and reached the Danube in rear of the Austrian army under Mack, which was at Ulm. The surprise was complete; Mack surrendered October 19th, and Napoleon then marched on Vienna, which he entered November 13th. But his position was critical. The Archduke Charles was approaching from Hungary, a Russian army was entering Moravia, and Prussia, incensed at the violation of her territory, joined the coalition. A short delay would have surrounded Napoleon with his enemies, but the czar was impatient, and the Russian army, with a small contingent of Austrians, encountered Napoleon at Austerlitz, December 2, 1805, and was signally defeated. This caused the break-up of the coalition; the Holy Roman Empire came to an end, the Confederation of the Rhine was formed under French protection, and the Napoleonic empire was firmly established. Napoleon then entered into negotiations for peace with Russia and England, endeavoring to conciliate those powers at the expense of Prussia. The negotiations failed, but Prussia was mortally offended, and mobilized her army in August, 1806, about which time Russia finally rejected the treaty with France. Napoleon acted with his usual promptitude, and advanced against Prussia before she could get help either from England or Russia. Although the rank and file of the Prussian armies was good, their generals were antiquated, and Napoleon crushed them at Jena and Auerstadt, October 14th, and entered Berlin on the 27th. He had then to carry on a stubbornly contested campaign with Russia. An indecisive battle at Eylau was followed by a hardly earned French victory at Friedland, June 14, 1807, and the peace of Tilsit ensued, by which Prussia lost half her territory, and had to submit to various humiliating conditions, while Russia escaped easily, and indeed got a share of the spoils.