The inspection of the Soviet military lasted for a month, and Colonel Mainz even traveled to the front lines to observe the ongoing battles.
In the northern Caucasus, the war unfolded between Tukhachevsky's Fifth Army and the White Army led by Denikin. At this time, Denikin had received substantial support from Europe and the United States, as well as a large quantity of weapons left over from the Allied armies after Kolchak's retreat.
Yet despite the aid, Denikin's forces failed to achieve victory. Tukhachevsky's Soviet troops crushed the White Army with ease, executing offensives as if chopping through vegetables. This campaign occurred about six months earlier than it had in historical records, likely initiated by the Soviets themselves to display their strength to military observers like Mainz.
The Soviet intelligence had already identified Mainz upon his arrival in Moscow, knowing he was a close confidant of Field Marshal Hindenburg, the true power behind Germany at the time. While this attention could have been dangerous, it actually facilitated Mainz's mission, giving him the opportunity to observe the war firsthand and witness the Soviets in action months in advance.
From his observations, Mainz gained valuable insight. The Soviet army's strength and discipline were impressive. Morale was high, and the bravery of the soldiers on the battlefield stood out. Tukhachevsky's command was precise and strategic, though the Soviets did not always seize every opportunity to exploit weaknesses in the enemy.
In contrast, Denikin's White Army performed clumsily. Despite having advanced weaponry supplied by the Entente, they repeatedly failed to capitalize on Soviet mistakes and even exposed additional vulnerabilities. Tukhachevsky exploited these flaws mercilessly, launching relentless pursuit operations. In just five days, five major battles broke out, decisively routing the White Army.
By the end of the Caucasus campaign, the Soviets had suffered over 20,000 casualties but annihilated approximately 120,000 White troops. Only the intervention of the Allied navies, which blocked the Kerch Strait, saved Denikin's forces from total destruction in Crimea.
Mainz mentally reassessed the situation. Before arriving in Moscow, he had secretly hoped the civil war might drag on, allowing Germany to profit from arms sales to the Soviets. But now, it was clear that the war would likely conclude within two or three years.
With the domestic White Army proving ineffective, the Soviet Union's primary adversaries in the final stages of the civil war would shift to foreign interventionists, especially Allied-backed forces. Mainz knew that any future consideration of external enemies, like those in the north, would need careful observation—but there was no rush.
By this time, Mainz had already taken a train to the Russian Far East to conduct further investigations.
On June 22, 1919, as his train reached Yakutsk, a telegram arrived from the Weimar Republic. It reported that on June 21, the former German High Seas Fleet had carried out a mass self-sinking operation at the Sparka Bay naval base under Rear Admiral Reut's command. Fifty-four capital ships were deliberately sunk, disappearing into the icy depths.
The operation shocked the world. The Allies, particularly Britain, viewed the fleet as spoils of war and considered the self-sinking an affront. Rear Admiral Reut was imprisoned and charged as a war criminal for destroying what the British considered Royal Navy property.
Meanwhile, in Germany, the event was hailed as heroic. Newspapers, including Der Spiegel, celebrated Reut and the sailors of the High Seas Fleet as national heroes. The story stirred immense national pride and inflamed anti-Entente sentiment across the Weimar Republic.
The political tension reached a boiling point at the ongoing Iron Tower City Peace Conference, which had already been embroiled in disputes for over six months. The actions of the High Seas Fleet had added fuel to the fire, pushing negotiations to an even more volatile and critical stage.