Enthusiasm for the war in 1914 was also high in Innsbruck. From the "Gott, Kaiser und Vaterland“ der Zeit angetrieben, begrüßten Bauernsöhne und Studenten den Krieg zum allergrößten Teil einhellig. Klerus und Presse stimmten in den allgemeinen Jubel mit ein und heizten die Sache weiter an. Besonders „verdient“ machten sich dabei auch Theologen wie Joseph Seeber (1856 – 1919) und Anton Müllner alias Bruder Willram (1870 - 1919) who, with her sermons and writings such as "Das blutige Jahr" elevated the war to a crusade against France and Italy.

Many Innsbruckers volunteered for the campaign against Serbia, which was thought to be a matter of a few weeks or months. Such a large number of volunteers came from outside the city to join the military commissions that Innsbruck was almost bursting at the seams. Nobody could have guessed how different things would turn out. Even after the first battles in distant Galicia, it was clear that it would not be a matter of months.

In 1915, the Kingdom of Italy entered the war on the side of France and England. This meant that the front went right through what was then Tyrol. From the Ortler in the west across northern Lake Garda to the Sextener Dolomiten the battles of the mountain war took place. Innsbruck was not directly affected by the fighting. However, the war could at least be heard as far as the provincial capital, as was reported in the newspaper of 7 July 1915:

„Bald nach Beginn der Feindseligkeiten der Italiener konnte man in der Gegend der Serlesspitze deutlich Kanonendonner wahrnehmen, der von einem der Kampfplätze im Süden Tirols kam, wahrscheinlich von der Vielgereuter Hochebene. In den letzten Tagen ist nun in Innsbruck selbst und im Nordosten der Stadt unzweifelhaft der Schall von Geschützdonner festgestellt worden, einzelne starke Schläge, die dumpf, nicht rollend und tönend über den Brenner herüberklangen. Eine Täuschung ist ausgeschlossen. In Innsbruck selbst ist der Donner der Kanonen schwerer festzustellen, weil hier der Lärm zu groß ist, es wurde aber doch einmal abends ungefähr um 9 Uhr, als einigermaßen Ruhe herrschte, dieser unzweifelhafte von unseren Mörsern herrührender Donner gehört.“

Until the transfer of regular troops from the eastern front to the Tyrolean borders, the national defence depended on the Standschützen, a troop consisting of men under 21, over 42 or unfit for regular military service.

The front was relatively far away from Innsbruck, but the war penetrated civilian life. This experience of the total involvement of society as a whole was new to the people. Barracks were erected in the Höttinger Au to house prisoners of war. Transports of wounded brought such a large number of horribly injured people that many civilian buildings such as the university library, which was currently under construction, or Ambras Castle were converted into military hospitals. The Pradl military cemetery was established to cope with the large number of fallen soldiers. A predecessor to tram line 3 was set up to transport the wounded from the railway station to the new garrison hospital, today's Conrad barracks in Pradl. The population in Innsbruck suffered from shortages, especially in the last winter, which was known as the Hunger winter went down in European history. In the final years of the war, food was supplied via ration coupons. 500 g of meat, 60 g of butter and 2 kg of potatoes were the basic diet per person - per week, mind you. Archive photos show the long queues of desperate and hungry people outside the food shops.

In October 1918, the first air raid alert was sounded, but no damage was done. At this time, most people were already aware that the war was lost and what fate awaited Tyrol, as this article from 6 October 1918 shows:

 „Aeußere und innere Feinde würfeln heute um das Land Andreas Hofers. Der letzte Wurf ist noch grausamer; schändlicher ist noch nie ein freies Land geschachert worden. Das Blut unserer Väter, Söhne und Brüder ist umsonst geflossen, wenn dieser schändliche Plan Wirklichkeit werden soll. Der letzte Wurf ist noch nicht getan. Darum auf Tiroler, zum Tiroler Volkstag in Brixen am 13. Oktober 1918 (nächsten Sonntag). Deutscher Boden muß deutsch bleiben, Tiroler Boden muß tirolisch bleiben. Tiroler entscheidet selbst über Eure Zukunft!“

On 4 November, Austria-Hungary and the Kingdom of Italy finally agreed an armistice. This gave the Allies the right to occupy areas of the monarchy. The very next day, Bavarian troops entered Innsbruck. Austria's ally Germany was still at war with Italy and was afraid that the front could be moved closer to the German Reich in North Tyrol. Fortunately for Innsbruck and the surrounding area, however, Germany also surrendered a week later on 11 November. This meant that the major battles between regular armies did not take place.

Nevertheless, Innsbruck was in danger. Huge columns of military vehicles, trains full of soldiers and thousands of emaciated soldiers making their way home from the front on foot passed through the city. The city not only had to keep its own citizens in check and guarantee rations, but also protect itself from looting. In order to maintain public order, defence groups were formed from schoolchildren, students, workers and citizens. On 23 November 1918, Italian troops occupied the city and the surrounding area. Mayor Greil's appeasement to the people of Innsbruck to hand over the city without rioting was successful. Although there were isolated riots, hunger riots and looting, there were no armed clashes with the occupying troops or even a Bolshevik revolution as in Munich.

Places of remembrance of the First World War in Innsbruck are mainly found at churches, which commemorate the fallen parishioners, and cemeteries. The Kaiserjägermuseum on Mount Isel displays uniforms, weapons and pictures of the battle. Streets in Innsbruck are dedicated to the two theologians Anton Müllner and Josef Seeber.