Complex sentence: In June, two days after the Soviets issued an an ultimatum demanding Bessarabia, Bukovina, and the Hertza region from Romania, the Romanians caved to the Soviet demands and the Soviets occupied the territory.
Split into simpler sentences: In June, the Soviets issued an an ultimatum demanding Bessarabia, Bukovina, and the Hertza region from Romania. Two days after the Soviet entry, the Romanians caved to the Soviet demands and the Soviets occupied the territory.