BERLIN (Reuters) -Tens of thousands of people across Europe marched in protest against Russia’s invasion of Ukraine on Sunday, the fourth day of the biggest assault on a European state since World War Two. More than 100,000 people gathered in central Berlin, carrying signs reading: “Stop the War”, “Putin’s last war” and “We stand with Ukraine” along with Ukrainian and European Union flags. Train and underground service was interrupted in some parts of the German capital as thousands flooded toward the Brandenburg Gate, near the Russian embassy. The protest came as missiles rained down on Ukrai…