Then consider the death toll: 27 million Soviet citizens dead, according to one estimate.
Horrifying events that took place on Russian soil, such as the Siege of Leningrad and the Battle of Stalingrad, are not forgotten.
This week, that's especially important.
Remember that in Russia, May 9 is Victory Day: the anniversary of the day that the Soviet Union announced that Nazi Germany had surrendered.
And Victory Day isn't just a big day for Russia.
It's a big day for all former members of the Soviet Union who fought together in the war.
This year, it may be an exceptionally complicated day for one country in particular: Ukraine.
In the past, Ukraine and Russia have celebrated Victory Day together on May 9 – for example, on May 9, 2010, Russian and Ukrainian sailors in Sevastopol marched in a joint parade to commemorate the 65th anniversary of the day on the orders of then-President Viktor Yanukovych.
But there's also been controversy.
To some Ukrainians, World War II was a fight against both Nazi Germany and the Soviet Union.
Ukrainian nationalists fought against the Soviet army at some points during World War II — some, such as nationalist idol Stepan Bandera, sided with Nazi Germany for part of it.
Even before the Euromaidan protests spun Ukraine into crisis, there was contention over the history:
In 2011, Yanukovych revoked a "Hero of Ukraine" award that had been given to Bandera by his predecessor and criticized the Western city of Lviv for failing to celebrate Victory Day appropriately.
Things are even more fraught now, of course, with Russia's military build-up on the borders an unpleasant reminder of Soviet domination, and Ukrainian nationalist groups such as Pravy Sektor accused of being "fascists."
On the 69th anniversary of the end of World War II, some people seem to believe history is repeating itself.
So, May 9 will be an important date to watch.
Back in March, there were rumors in Russia that Ukraine may ditch their celebrations on that day, and choose to go with May 8, the exact date of Germany's surrender celebrated in many other countries as Victory in Europe Day (the different date is due to time zone differences).
While that doesn't appear to be true, it does seem that Kiev has cancelled plans for a traditional military parade, and will instead hold a prayer service for the victims of World War II on May 9.
Members of the Ukrainian nationalist party Svoboda are also seeking to have a prominent symbol of Russian military valor, the St. George Ribbon, prohibited, in spite of (or more likely, because of) the fact that many pro-Russian separatists in the east are wearing it.
AFP reports that the Red Poppy, used to remember war dead in other countries, will be used on Victory Day instead.
It's difficult timing.
On Wednesday, Russian President Vladimir Putin asked pro-Russian separatists in eastern Ukraine to postpone their proposed referendums on independence planned for May 11, a move that appears to show a new Russian desire for a de-escalation of the conflict.
The announcement left many pro-Russian separatists confused.
It'll certainly be interesting to see how they react May 9.
Source: The Washington Post