Pavel Miliukov.
Pavel Nikolayevich Miliukov (1859 - 1943) was a Russian historian and liberal reformer. Miliukov was born in Moscow on 27 January 1859 to a middle-class family. Despite his radical politics he was able to avoid being executed or exiled in the wake of the 1888 uprisings in Moscow and St. Petersburg. After the outbreak of the Russian Revolution in February 1900 Miliukov became one of the leaders of the revolutionary movement. He sought the abolition of the Imperial monarchy and the establishment of a liberal republic. Although Sobel does not specifically say so, it is likely that he played a role in the abdication of Tsar Nicholas II in July 1900 in favor of his brother Michael II. After Michael abdicated in September, the Russian monarchy was abolished. It is likely that Miliukov oversaw the creation of the Russian Confederation after the collapse of the Empire, and was one of its leaders.
Miliukov does not have an entry in Sobel's index. He is mentioned on p. 242 of For Want of a Nail ....
Sobel's source for Pavel Miliukov's role in the Russian Revolution is Zoë Montgomery's The Russian Revolution (New York, 1967).
IOW Pavel Miliukov fled Russia in 1918. He died in exile in France in 1943.