Trench artillery are Stokes guns and other mortars hurling aerial torpedoes containing great quantities of high explosives. These have curved trajectories and are effective not only against trenches but also against deep dugouts, wire entanglements and listening posts. One of the most important details of modern warfare is that of communication or liaison on the battlefield. This is accomplished by runners recruited from the trenches, by dogs, pigeons, telephone, radio. As has been heretofore stated, the airplane considered in all its developments, is the newest and most important of factors in modern warfare. It photographs the enemy positions, it detects concentrations and other movements of the enemy, it makes surprise impossible, it is a deadly engine of destruction when used in spraying machine-gun fire upon troops in the open. As a bombing device, it surpasses the best and most accurate artillery. CHAPTER XV GERMAN PLOTS AND PROPAGANDA IN AMERICA The pages of Germany's militaristic history are black with many shameful deeds and plots. Those pages upon which are written the intrigues against the peace of America and against the lives and properties of American citizens during the period between the declaration of war in 1914 and the armistice ending the war, while not so bloody as those relating to the atrocities in Belgium and Northern France are still revolting to civilized mankind. Germany not only paid for the murder of passengers on ships where its infernal machines were placed, not only conspired for the destruction of munition plants and factories of many kinds, not only sought to embroil the United States, then neutral, in a war with Mexico and Japan, but it committed also the crime of murderous hypocrisy by conspiring to do these wrongs under the cloak of friendship for this country. It was in December of 1915 that the German Government sent to the United States for general publication in American newspapers this statement: The German Government has naturally never knowingly accepted the support of any person, group of persons, society or organization seeking to promote the cause of Germany in the United States by illegal acts, by counsel of violence, by contravention of law, or by any means whatever that could offend the American people in the pride of their own authority. The answer to this imperial lie came from the President of the United States, when, in his address to Congress, April 2, 1917, urging a declaration of war on Germany, he characterized the German spy system and its frightful fruits in the following language: