At the end of October, after more than half a month of preparation, the Romanian army finally set off.
The 150,000-strong Romanian force crossed the border and began its offensive toward Austria.
However, the strategic advantage was no longer fully on their side. After the surrender of the Italian army, all of Germany's other enemies had been neutralized, leaving only the Romanians in the east.
By now, Walter Model's forces had grown to 150,000 troops. The 100,000 weapons captured from the Italians gave the German army sufficient equipment to expand its ranks. Mainz also recruited Austro-Hungarian World War I veterans, integrating them with the German units and coordinating with local militias to form a defensive line in northeastern Austria.
Just as Mainz prepared to engage the Romanian army, an unexpected visitor arrived from Vienna.
"General, why are you here?"
Field Marshal General Ruprecht of the Second Reich had come, surprising Mainz. Wasn't he supposed to be at Hindenburg's barracks?
"Hehe, don't be surprised. Paul sent me. I'm planning a trip to North America and wanted to check in on the situation here. If you need help, I'll assist as much as I can."
Ruprecht's official purpose was to inquire about North America, but his real concern was the Austrian front. Hearing that the Romanians were advancing, he made an excuse to Hindenburg and arrived, slightly relieved. He intended to depart for North America afterward and might not return to Germany, as his special status would make a return politically complicated.
Mainz nodded, accepting Ruprecht's presence under Hindenburg's authorization. Nevertheless, he increased surveillance over him, citing security measures.
With that matter settled, Mainz focused on the final confrontation.
The Romanian army advanced cautiously, revealing few weaknesses. It took a week to cross the Fierce Tooth mountains and enter Austria.
General Banthner, aware of past militia insurgencies, sent cavalry to scout for enemy positions. The German forces could do little to impede this careful advance. Day by day, the Romanians neared Vienna.
"Why aren't they attacking yet?"
Although unopposed, Banthner felt uneasy. He knew the Germans were elite, having defeated strong enemies quickly. Facing an opponent initially 50,000 strong, he might have underestimated them. Now, with both sides at roughly 150,000, the enemy's inaction seemed suspicious.
"There must be a demon at work," Banthner thought, sensing something amiss.
"General, we're less than 100 kilometers from Vienna. In two days, we can be at the Golden Hall for a concert!"
The subordinates, unaware of danger, cheered. As noble-born officers, many appreciated music, so the thought of Vienna's cultural splendor lifted morale.
Banthner forced a smile, setting aside his doubts. The troops were in the city's vicinity—he needed to secure Vienna first.
The next day, the Romanians captured Fischamend, an important town south of Vienna. Yet the Germans remained unseen. Even Banthner felt a fleeting relief.
"They must have retreated. The plain around Vienna is flat; they'd avoid engaging us here."
He convinced himself of this and reassured his men.
"Hehe, since they've retreated, Vienna is ours!"
The troops, seeing the Golden Vienna ahead, became frenzied with greed. Vienna, capital of the Habsburg Empire, was wealthy and culturally rich. Nobles hoped for future advantage; commoners sought loot and women.
"General, order the attack! The brothers can't wait!"
A noble officer licked his lips, green with excitement.
"Alright, attack!"
Banthner's unease peaked, but he could not resist the army's will. As the order was given, a foreboding tension settled over him.