A century ago, imperial dreams were common among major nations of the world -- Britain, France, Germany, Japan, and even the United States all had them.

Most evaporated in the traumas of World War II and its aftermath. Yet the Soviet Union's multinational empire, subordinating peoples of more than a dozen distinct nationalities to ethnic Russian rule, lived on, until the Soviet collapse of 1991.

The jewel of that Soviet empire was Ukraine, a vast and abundant breadbasket inhabited by more than 40 million people, generating over 10 percent of the world's exports of feed grains.

Kent Calder. (Kyodo)

With formidable military-industrial capabilities that crucially supported Soviet global power, Ukraine was also home to the Soviet Union's largest port, Odesa.

That ice-free harbor town and naval base also served as the Soviet Union's southern window on the Balkans, the Middle East, and the wider world.

For nearly two centuries, Odesa was literally a crown jewel of the Russian empire, albeit a diverse and cosmopolitan one. The city was founded in 1794 by decree from Empress Catherine the Great, only two years after a major Czarist military triumph over Turkey expanded imperial Russia's borders southward to the shores of the Black Sea.

For four decades (1819-1859) Odesa served as a free port, attracting a dynamic and diverse mixture of entrepreneurs to Russian shores. By the end of the nineteenth century, Odesa was the fourth largest city of the entire Russian empire, with a population half Russian, 37 percent Jewish, and only 9 percent Ukrainian.

Over time, Odesa forged close bonds to Soviet power, in part through its stout resistance to the Nazis. The city resisted a ferocious German and Rumanian onslaught for over two months in the summer of 1941, and remained restive throughout the war.

Around 100,000 of its Jewish residents were murdered by the Nazis, including close to 30,000 in the infamous Odesa Massacre of October, 1941.

At war's end, in a tribute to its fierce resistance, Odesa was one of four locations across the entire country to be first named a Hero City of the Soviet Union, together with Stalingrad, Leningrad, and Sevastopol in the Crimea.

Given its history, its past standing as a jewel of the Soviet empire, and its current strategic importance, Odesa naturally figures strongly in Vladimir Putin's imperial dream of reviving the former Soviet Union.

If he can reclaim Odesa, Putin can effectively cut Ukraine off from the sea, dealing a crippling blow to its export potential and long-term prospects for economic independence.

That would be a major step toward bringing a defiant Ukraine into subordination to Moscow, although prospects must be clouded by recent demographic shifts in Odesa, which is now over two-thirds Ukrainian and only an estimated 25 percent Russian.

Blocking Ukraine's maritime access by occupying Odesa, in the context of continuing international sanctions against Russia, would also have major implications for global commodity markets.

In 2020 Ukraine and Russia together exported 28 percent of the wheat, 26 percent of the barley, and 16 percent of the corn being exchanged in international trade.

Odesa was one of the largest grain export sites in the world, especially for corn and barley. Interruption of its export capabilities due to the Ukraine war has already led to a catastrophic spiral in grain prices, affecting especially the poorest of the poor, across the Middle East, Africa, and South Asia, all of which are heavily reliant on Black Sea exports.

Given its strategic importance, the fate of Odesa could also influence the future contours of the Ukraine war itself, and the fate of international sanctions against Russia even following the war.

The contours of the conflict, in turn, will influence not only food, but also energy and other commodity prices. America's ban on energy imports from Russia has already led to a spike in global oil prices, despite President Joe Biden's recent release of 180 million barrels from the U.S. strategic petroleum reserve.

European nations have also announced plans to steadily decrease reliance on Russian gas and oil, which should certainly come into effect if the conflict continues.

The most salient commodity issue, above all, is Russian natural gas exports. Germany and France, in particular, are heavily exposed, with 43 and 27 percent dependence on Russian gas, respectively, with Japan ranking fifth, at 9 percent.

Since natural-gas demand is cyclical, due to the changing of the seasons, demand begins to rise sharply in Europe during the months of May and June, in preparation of stockpiles for the following winter.

The progress of the war during April and early May, especially in Black Sea coastal ports like Odesa, could thus indirectly have a significant impact on natural-gas prices in Europe, and by extension worldwide.

This raises the issue of the Ukraine war's conclusion, and the fate of Putin's imperial dream. As May 9 is Victory Day in Russia, to commemorate the Soviet victory in World War II, it will be auspicious for Putin to have achieved some sort of outcome that he could represent, in whatever contorted fashion, as victory.

No doubt Russia's current redeployment of forces toward eastern Ukraine, including the Donbas, will shorten supply lines and allow greater concentration of forces.

Yet in the face of rising Western support for Ukraine, and apparent Chinese reluctance to provide large-scale assistance to Russia, prospects for dramatic Russian breakthroughs remain problematic in coming weeks.

How far will Putin pursue his imperial dream? And will that take him to Odesa, that crown jewel of Empress Catherine the Great before him? That struggle, for a place in Putin's imagined imperial history, is unfolding before us now.

(Kent E. Calder is the vice dean for Academic Affairs of the Johns Hopkins School of Advanced International Studies in Washington and director of the Edwin O. Reischauer Center for East Asian Studies at SAIS.)