Poster for the Anti-Semitic documentary “Der ewige Jude” (The eternal Jew)
Produced by the Nazi Party in 1940
Hitler believed that while the German people died in the front for the fatherland, the Jews were busy plotting against Germany, profiteering from the war and gaining political position. In fact Hitler was not alone in his views, and many accusations against the Jews spread throughout Germany during and after WWI; the main one: lack of patriotism. This rumour reached the highest echelons of the German government and in 1916 the High Command ordered a census to confirm these allegations. Known as “the census of the Jews” (Judenzählung), it attempted to find if the Jews were really avoiding their patriotic duty during the war. But the results were never published; which spread even further an anti-Semitic sentiment throughout Germany –as many anti-Semitic groups used the government’s silence as confirmation of their claims-. 
So… was it true; were the German-Jews conspiring against Germany from the inside? Well… yes and no.
In regards to the lack of patriotism, the allegations were completely false; the Jews had the highest rate of representation in the German army from any other ethnic minority; a rate that was at least as high as that of the Bavarian non-Jewish population -bastion of German nationalism.  Over 100,000 out of a total German-Jewish population of 550,000 served during WWI; 12,000 Jews perished fighting for Germany, and another 32,000 were decorated for bravery.  As a matter of fact, Hitler’s First Class Iron Cross was awarded by recommendation of his Jewish commanding officer, Lieutenant Hugo Gutmann. 
Now, in regards to the Jews fighting against the Germany of the Kaiser that Hitler supported –the undemocratic Old World Order which prevented ethnic minorities from ever achieving full emancipation- this was true in most cases; and why not? Even though the situation of the German-Jews gradually improved since the turn of the century, they were still discriminated in many aspects; situation that was aggravated by the fact that all lower classes, whatever the ethnic background, also suffered from the discrimination and the exploitation of the ruling classes. Under those circumstances many Jews turned to left-wing ideologies like socialism, and fought not only for the end of ethnic discrimination, but also for the equality between classes.  These were the so called “Liberal-Jews”; and even though they had a different political view from the Kaiser and his supporters, their ideals were also shared by many Germans who thought Social Democracy was the best solution to Germany’s problems.
These Liberal-Jews didn’t seem to be the cause of the problem for Hitler; and even he wasn’t much concerned about them at first. After all, they were also Germans, but from a different religion; and he condemned the attacks of the German anti-Semitic groups against the Jews for religious reasons; saying that such an attitude was unworthy of the German people. But during Hitler’s period in Vienna, and due to the large number of Jews that lived there under hardship –unlike in Linz- he began to entertain the idea that the Jews might not be Germans after all, stating in his Main Kampf: “Yet I could no longer very well doubt that the objects of my study were not Germans of a special religion, but a people in themselves; for since I had begun to concern myself with this question and to take cognizance of the Jews, Vienna appeared to me in a different light than before. Wherever I went, I began to see Jews, and the more I saw, the more sharply they became distinguished in my eyes from the rest of humanity. Particularly the Inner City and the districts north of the Danube Canal swarmed with a people which even outwardly had lost all resemblance to Germans.”
But even then, Hitler had many doubts; and during those times he claims to have being tormented by a fear of doing injustice to the Jews. However, during his study of the Jewish question, Hitler came across a new Jewish movement that was gaining strength throughout the world; a radical movement that exalted the Jewish national character and aimed no less that for a Jewish homeland and self-determination for the Jewish people:  “And whatever doubts I may still have nourished were finally dispelled by the attitude of a portion of the Jews themselves. Among them there was a great movement, quite extensive in Vienna, which came out sharply in confirmation of the national character of the Jews: this was the Zionists.” It was all clear for Hitler now; the Zionists had confirmed that the Jews were not really Germans, and therefore their loyalty must lay elsewhere.
It didn’t matter to Hitler whether or not only a small portion of Jews supported Zionism, while the vast majority were Liberal-Jews that rejected it; the Jews had confirmed their distinct character as a nation, and therefore for him any disagreements between them was just a matter of forms: “It looked to be sure, as though only a part of the Jews approved this [Zionist] viewpoint, while the great majority condemned and inwardly rejected such a formulation. But when examined more closely, this appearance dissolved itself into an unsavory vapor of pretexts advanced for mere reasons of expedience, not to say lies. For the so-called liberal Jews did not reject the Zionists as non-Jews, but only as Jews with an impractical, perhaps even dangerous, way of publicly avowing their Jewishness. Intrinsically they remained unalterably of one piece. In a short time this apparent struggle between Zionistic and liberal Jews disgusted me; for it was false through and through, founded on lies and scarcely in keeping with the moral elevation and purity always claimed by this people."
It was at that moment when Hitler experienced what he called “his greatest transformation”, and succumbed to anti-Semitism. From that moment on he would be disgusted at the sole thought of a Jew; and he couldn't stand their gradual integration in all aspects of German life: art, literature, the press, finances, and even politics; the Jews were everywhere! And there could be no coincidence; since all of them were Jews, and according to the Zionists the Jews were a nation, they could only be part of the same plot; a plot controlled from outside Germany on which every Jew played his role; no matter how opposite their ideologies were: “I began to study again, and now for the first time really achieved an understanding of the content of the Jew Karl Marx's life effort. Only now did his Capital become really intelligible to me, and also the struggle of the Social Democracy against the national economy, which aims only to prepare the ground for the domination of truly international finance and stock exchange capital.”
… Next Chapter: Hitler’s Struggle (part V: Hitler and the Bankers)
Adolf Hitler, “Mein Kampf”, Eher Verlag, Munich, 1925
 Bavarian National Exhibition, “Deutsche Jüdische Soldaten”, the Military Research Office of the Federal German Defence Forces; cited in: Herbert Loebl, “Juden in Bamberg”, 2002, [accessed from www.juden-in-bamberg.de]
 Bryan Mark Rigg, “Hitler’s Jewish Soldiers”, p.72, University Press of Kansas, 2002
 Robert Payne, “Life and Death of Adolf Hitler”, Dorset Press, 1995
 Ashley Lazarus, “Faith and Fate, the history of the Jewish people in the 20th century: Episode I, The Dawn of the Century“, Berel Wein/Destiny Productions, 2007
 Wikipedia: Zionism (http://en.wikipedia.org/wiki/Zionism)