With the start of World War I, several facets of the war progressed. With new advancements came new opportunities for schemers to flex their muscles in the world of espionage and offensive action. This research will focus on intelligence operations relevant to the offensive and espionage in the naval warfare of the First World War. It will focus primarily on German and British naval initiatives, but will not neglect those of Russia, France and the United States. Any guesses made throughout will be made taking into account a given party's incentives to make misrepresentations as well as the anticipated gains attributed to each action initiated. World War I produced a considerable increase in the flow of diplomatic, military, and naval relations. intelligence. What is perhaps more interesting is how little attention the Foreign Office paid to it. The greatest intelligence advance of the war was the revival of British codebreaking after an interval of seventy years – a renaissance in which the Foreign Office had nothing to do. The initiative came from Director of Naval Intelligence, Admiral Reginal "Blinker" Hall, who founded a diplomatic annex to the Admiralty's wartime signals unit, Room 40, under personal control at the In the summer of 1915. During the Dardanelles campaign in 1915, he sent secret information. emissaries to Constantinople with authority to offer up to £4 million to secure passage for the British fleet. Hall's actions surrounding the Irish Easter Rising in 1916 prove to be something worth a second look. Hall learned of Germany's plans to land both German arms and Irish nationalist Sir Roger Casement on the west coast of Ireland. Hall did not inform the Foreign Office or the Irish government. Dublin Castle gained the knowledge...... middle of paper ...... submarine warfare also came with the recognition that such actions would likely result in the United States entering the war. Arthur Zimmermann thought he would distract America by getting Mexico to wage war against it. He was confident that Mexico would accept the offer of restitution for territories lost in the Mexican-American War of 1846. However, the British intercepted the message, Room 40 deciphered it, and Woodrow Wilson was quickly informed. Wilson delivered it to the press and five weeks later America declared war on Germany. World War I changed the way wars were fought. Espionage in particular has made enormous strides in becoming an integral part of warfare. From submarines to sabotage, telegrams to minefields, naval warfare has shaped the course of war. If the codes had not been deciphered and the messages intercepted, the world would be very different today..