Khalkhin Gol — Baïn-Tsagan

In early July 1939, the Japanese go on the offensive at Khalkhin Gol. On the night of 2–3 July, they cross the river to the north and seize Mount Baïn-Tsagan, on the west bank held by the Soviets. If they dig in there and burst into the rear of the Soviet dispositions, Zhukov's entire front risks collapsing.

Zhukov gauges the danger within hours. His armoured brigades are available, but the supporting infantry and the artillery are still far off or in the midst of regrouping. Cautious doctrine would have him wait until he has assembled balanced combined-arms forces before counter-attacking.

But time works against him: every hour left to the Japanese allows them to entrench themselves on the height. Three options present themselves. To launch the tanks alone immediately in an assault on the hill, without waiting for the infantry, at the cost of heavy losses but to seize back the initiative? To wait to regroup a complete combined-arms force, letting the enemy dig in? Or to fall back to establish a new line to the rear? The decision is taken under pressure.