 The First World War is really the beginning point of the modern American army. A soldier today would recognize the battlefield of the First World War, whereas a soldier in say, even as late as the 1890s, would be very confused. So it's really the origin point of what we consider modern conventional warfare. One of the reasons why the American public has such a difficulty understanding the war is because they don't really know why we joined. There is no great spark. There is no Pearl Harbor moment. What happens is the war breaks out in August of 1914. It's a conflict between the great European empires. It is an outgrowth of an international diplomatic system that is based upon competition that we want to stay out of. American relations with Europe were very different than they are today. We had a much closer connection with the French stemming from both of our revolutions. The relations between the United States and the rest of the continent were fairly strained. There are a lot of divisions. This is a time when a lot of Americans are immigrants, either first or second generation, and they hold a lot of ties to Europe. President Woodrow Wilson decided to support a position of neutrality. He argued that the United States as a neutral country was free to essentially go about its business trading with either side and that we would not show favor to one or the other. Wilson's call to the American public is that he wanted them to be neutral in thought as well as deed. The British have a very different idea of this. They very quickly establish a blockade of Germany. So there is actually a very natural evolution of American relations in terms of economics during the war where we start supplying the allies and have a much larger trade relationship with the allies than we do with the Central Powers by virtue of the blockade and also by virtue of the sophisticated economic system already operating within Britain. They start running out of money. They start loaning, giving huge loans to their allies. Over the course of the war, what we see is that the United States starts to fill that gap and starts to provide more and more credit to the allies. And in fact, the United States, by the time we go into the war, has supplanted Great Britain as the international creditor. It's going to impact Wilson's thinking, it's going to give him influence over what the allies do. When he talks about advocating for peace without victory, he actually means a peace based upon mutual agreement where one side does not gain to the disadvantage of another, that in fact they all come together and create an equitable peace. He changes due to what he perceives as the growing threat of Imperial Germany. Probably the most important action that Germany takes that leads directly to the United States being involved in the war is the usage of what's called unrestricted submarine warfare. It is a type of commerce rating. If a combatant was going to target an enemy's commerce, typically what you would do is you would intercept a vessel on the high seas, you would stop it, you would indicate that you were going to sink it, and you would allow the crew to depart. One of the problems with this is that the U-boats are very vulnerable on the surface and the British are going to start arming merchant vessels. So the Germans decide instead that they're going to declare that any vessels found within a certain zone around the British Isles are fair game. They will not surface, they will go ahead and just fire upon them and sink them. And this is seen as really an affront to international law. The most famous sinking is of course the Lusitania. Or when the Germans sink the Lusitania, killing over a thousand people including over a hundred Americans. The American public is horrified. President Wilson is very angry, of course. Several months later the Germans sink another vessel, killing a couple more Americans, and the United States threatens to suspend diplomatic relations with Germany. Germany at this point makes a decision, makes a strategic decision that they are not willing to risk war against the United States at this point. So in fact they make a pledge and they agree that they will suspend unrestricted submarine warfare. And they do. Circumstances are going to change very rapidly in 1917. The Germans looking at the strategic situation that they're facing in the war make a determination. The German Navy essentially argue that if they resume unrestricted submarine warfare they can sink enough British shipping to knock the British out of the war before the United States can transport an army to Europe. This kind of sets in motion the events that are going to lead to the United States declaring war. Obviously the other big element will be the Zimmerman telegram. So the German Foreign Office starts to think about ways how this anticipated American intervention can be counteracted. They come up with Mexico. Mexico was a neutral country at the time, was driven by civil war, but nevertheless it was a neutral country. So the German Foreign Secretary Arthur Zimmerman decides to make an alliance offer to Mexico. And he tells the Mexicans we intend to declare unrestricted submarine warfare. If the United States indeed then declares war against us we make you an offer. You go ahead, declare war on the United States. We'll help you, we'll give you money, some other unspecified support. The Germans were then hoping well even if the United States declares war on us all their troops will be tied up on the border with Mexico and therefore this American intervention into the war won't matter. Normally and in peacetime they would have sent this message by submarine cable. The problem was that in 1914 when the war broke out the Royal Navy had retrieved this German submarine cable and had destroyed it. They came up with a pretty ingenious solution. They enlisted the help of the Americans. There was still an American Embassy in Berlin. So the German Foreign Office approached the American Embassy in Berlin and asked them, well, you know, can you help us? We have an important message for our ambassador in Washington and we can't relay this by cable because the evil British have cut the cable. So the American Embassy then sent this message on their own cables from Berlin to the State Department of Washington DC not knowing what was in there. Well, what neither the Americans nor the Germans knew was that the British was intercepting all American traffic that was going through London. This message was routed through the American Embassy in London. They wanted to know what the Americans were thinking. You know, they were neutrals but an important neutral. So this Zimmerman telegram as it then became known almost by accident landed in the lap of British naval intelligence. They decrypted it. They saw very quickly this is not an American message. This is a German message, a very interesting German message. They see this is very explosive and they would like to give this to the Americans. But they can't do it at this point because the Americans would probably ask, this is very interesting, but where did you get this message from? And the British can't really say, well, you know, we're routinely reading your traffic. So they also then retrieved the second message that the German ambassador from Washington sends to Mexico City. This is the copy they then give the American ambassador in London with the not entirely true but also not untrue explanation that this message was obtained in Mexico City. Wilson had still viewed the international system as the main culprit for the war. However, he looks at unrestricted submarine warfare. He looks at the Zimmerman telegram. He looks at Germany's militaristic nature. And he sees in Germany an autocracy. And he sees Germany as a threat to international peace. He sees Germany as a threat to democracy. In Wilson's war message, he specifies very clearly that the United States is going to wage war against the government of Imperial Germany, not against the German people. And that we're waging war against what he sees as an autocratic, militaristic, dictatorial regime that is a threat to international peace and that the German government has to be checked. So the object is not necessarily to defeat the German people. It's not to annihilate Germany as a country. It is to defeat and overthrow the German autocratic regime and make it so that democracy can spread.