XLIX. Submarine Warfare 182 PART VI.--THE UNITED STATES AND THE BELLIGERENTS L. The Old Menace 189 LI. The U-53's Exploits 194 LII. Gathering Clouds 200 LIII. Rupture With Germany 205 LIV. Nothing Settled 212 PART VII.--WESTERN FRONT LV. The German Retreat on the Ancre 217 LVI. The German Retreat Continues--French Recover 120 Towns 227 LVII. The British Troops Capture Vimy Ridge and Monchy--French Victories on the Aisne 239 LVIII. French Victories in Champagne--The British Capture Bullecourt 252 LIX. The Battle of Messines Ridge--British Smash the German Salient South of Ypres 263 LX. The Germans Defeat British on Belgian Coast--Intense Fighting in the Champagne and at Verdun 276 PART VIII.--THE UNITED STATES AND GERMANY LXI. The Interim 291 LXII. Berlin's Tactics 297 LXIII. Armed Neutrality 304 LXIV. Germany's Bid to Mexico 312 LXV. A State of War 317 LXVI. Building the War Machine 328 LXVII. Men and Money in Millions 344 LXVIII. Envoys from America's Allies 351 LXIX. In It at Last 356 PART IX.--THE RUSSIAN REVOLUTION LXX. Foreshadowing Revolution 363 LXXI. The Rise of Nihilism 365 LXXII. Revolutionary Doctrines 367 LXXIII. Russian War Spirit Aroused 372 LXXIV. Rasputin, the Evil Spirit of Russia 374 LXXV. Treachery of the Autocracy 378 LXXVI. Party Intrigues 380 LXXVII. The Work of Traitors 383 LXXVIII. Threatening of the Storm 386 LXXIX. Revolution 389 LXXX. The Culmination 392 LXXXI. The New Government 395 LXXXII. The Czar Abdicates 400