In the preceding chapter the growing maritime importance of petroleum has been shown, and it was therefore inevitable that in a conflict in which sea power was so decisive an influence that it should have been closely related to naval effort. Even if the uses of petroleum had been confined to one instrument of warfare merely--the submarine--it would have influenced the course of history and the fate of nations. Without petroleum the submarine as an effective agent in war could not have come into existence, and the whole story of the conflict from the winter of 1915 onward would have been different. Again, without petroleum no air-craft could have left terra firma, and military tactics based on the powers of observation provided by these “eyes of the army” would not have come into existence. It must also be admitted that the toll of destruction both on land and sea would not have been so great. It would not have been possible for any country to embark on a diabolical policy of destroying unarmed ships and unfortified cities, and wreaking vengeance on helpless non-combatants. But these crimes cannot be charged against petroleum itself, but rather against the ingenuity of men bent on destruction. These were but two instances of the part petroleum played in the war. It is no exaggeration to say that there was no phase of belligerent activity in which it was not an active agent. From the very outset of hostilities in August, 1914, discerning men in Allied countries foresaw that victory must rest with the side which commanded the greater reserves of petroleum. Thus from the beginning America, as the chief source of the world’s supply, was recognized as a factor of inestimable importance in the ultimate decision. Germany was as fully alive to this circumstance as her enemies. The high commands of the warring nations, from the very outset, took into consideration the desirability of securing possession of the oil fields in other lands. It was one of the aims of the British navy in driving German ships from the seas to prevent oil reaching the Central Empires from the Western Hemisphere. Later, when the blockade of Germany was definitely established and pressure was brought to bear against countries suspected of enabling Germany to obtain various classes of supplies by indirect purchase, petroleum products were regarded as the most important items in the extended list of contraband of war.