Fieldmarshal Klaus Schönhausen and his troops in Preßburg
|Großgermania|| Slovak Republic|
Order of Malta
| Michael von Preußen|
| Mikuláš Paška|
| 468,796 troops|
| 21,490 troops|
6 antitank companies
Although the declaration of war established no casus belli, a spokesman for the Großgermanian government later stated that the declaration and subsequent invasion was 'a direct response to terrorist activities being carried out against Großgermania from within Slovak territory'. In response to this claim, the Government of Slovakia, which effectively controls very little of the territory of Slovakia, issued a statement demanding that it not be held responsible for the actions of groups that 'are beyond the effective control of the Government' and claiming the invasion is a 'blatant attack on the sovereignty of the Slovak Republic'. Slovakia also filed a complaint with the United Nations General Assembly and the United Nations Security Council, of which Großgermania is an elected member.
At a Security Council meeting held on 10 July, the Großgermanian envoy presented evidence to the fifteen-member panel, as well as a delegation from Slovakia, that the Sovereign Military Hospitaller Order of Saint John of Jerusalem of Rhodes and of Malta, a Rome-based Catholic chivalric order, was using the territory of Slovakia to launch terrorist attacks on Großgermania, including several bombings and a foiled assassination attempt against Horst Köhler. The Slovak delegation reiterated to the Council that, due to its currently weak control of its territory, it should not be responsible for terrorist actions carried out within its borders. The member nations of the UNSC continued consultations well into the evening, but released no response to the invasion.
The Russian Federation, which still maintains troops in Großgermania following the suppression of a coup d'état in that country in early June, has thus far been the only nation to explicitly condemn the invasion. Many speculate Russia's shared borders with Slovakia make Russia view the invasion as a threat to its domestic security. According to a leak made to Pravda Online, the Großgermanian ambassador to Russia, Valentino Boos, met with Russian President Viktor Putyatin to quell these concerns, at which point he assured Russia that Slovakia was to remain an independent country following the invasion.
The Großgermanian assault was executed in three operations. The first operation involved moving the Luftwaffe against the Slovakian Air Force, in a swift and decisive move to decommission the numerically-superior force. The second operation, conducted by the Imperial Army, involved an invasion of eastern Slovakia from Silesia, with the army proceeding northwest trough the country, securing the rural, food-producing areas in order to isolate the cities in a form of modern siege warfare. The final phase of the invasion involved moving more than a quarter million ground troops, including the majority of tanks, in a blitzkrieg maneuver from Moravia and Opole towards the Slovak capital, Preßburg.
On Thursday, 23 July, the Slovak Government, led by President Mikuláš Paška, was captured and surrendered when Großgermanian troops captured the Preßburger Schloß (Preßburg Castle), the government's meeting hall and primary executive building. The majority of cities complied with the surrender, however, the troops in charge of Košice, Prešov, and Banská Bystrica continued to resist until 25 July, when Germanian troops launched a coordinated assault and forced their surrender. The First Army (spread throughout the country) has continued to meet sporadic resistance since then, both from government military and local paramilitary and militia forces.
The day following the initial surrender, Paška officially granted control of the country to the Second Großgermanian Army, which formally dissolved the Slovak Republic, establishing the Joint Military Command of Preßburg and Preschau (Gemischten Militärkommando Preßburg und Preschau, GMkPP), with Günter Kehrer, Commander of the Imperial Military, as Viceroy.
In mid-August, the GMkPP was dismantled, and a civilian government was established under the de facto control of the Imperial Government of Großgermania. Thusfar, only Großgermania itself recognizes the legitimacy of the new Slovak government.