Members of the United States Congress, Republicans and Democrats, rose to their feet time and again Wednesday night, nearly drowning out Ukrainian President Volodymyr Zelensky in one emotional standing ovation after another. It was an extraordinary evening, concluding an extraordinary day during a crucial moment in history. The entire day was geared to three audiences – the American people and its leaders, the Ukrainian people and Russian President Vladimir Putin. Zelensky’s message resonated loudly to all of them: From the moment he landed in the US, dressed in his trademark olive green clothes, to the warm welcome he received in the White House from President Joe Biden, to the rapturous reception in the Congress, a place where few foreign leaders receive the honor of speaking to a joint meeting of the two chambers. The visit aimed to convince Americans to continue supporting Ukraine, to show Ukrainians that there’s reason to remain hopeful and resilient and to prove to Putin that Ukraine is not about to let up. The Ukrainian president is an eloquent speaker, but the images alone spoke with soaring power. Biden’s hand on Zelensky’s shoulder. The warmth exuded by so many members of Congress as they greeted him. And then there were the words. Imagine being Putin, who just yesterday visited one of his very few allies, the president of Belarus, Alexander Lukashenko, and seeing the politically polarized United States come together to embrace Zelensky. Imagine Putin hearing Biden say, as he did in a press conference at the White House after speaking with Zelensky for more than two hours, “And it was very important for him and everyone else to see that President Zelenskyy and I are united, two countries together, to make sure he cannot succeed…. “It’s important for [Putin] to know that we are going to do everything in our power – everything in our power to see that [Zelensky] succeeds” The Ukrainian president finally had that visit to the White House he had requested years ago from President Trump, hoping that the image would deter Putin’s aggression. The visit would have to wait until a different American president, and it would be too late to prevent Putin’s assault. Zelensky made his historic trip at a crucial moment in what future generations may come to view as one of the defining conflicts of our time: the battle between democracy and autocracy, in which Ukraine today is the blazing, blood-soaked, shivering front line. He came to tell Americans “Thank you.” And he said it over and over. “I hope my words of respect and gratitude resonate in each American heart.” But that was only the first part of his message to the country that has supplied the weapons that have helped enable Ukraine to push back against a much bigger enemy: Zelensky came to explain why this is not just Ukraine’s fight. “Your money is not charity,” he assured a Congress about to debate billions more in military and economic support, where skeptical Republicans will soon have more influence. “It is an investment in the global security and democracy, that we handle in the most responsible way.” To continue what has been a successful defense against Russia, despite appalling human suffering, Zelensky had to persuade Americans – in Congress and at home – that Ukraine’s fight is a fight for the values of the free world. As Zelensky pleaded for continuing and growing support, he wouldn’t be so brazen, so blunt to phrase it directly, but we should know the truth: He may be saying thank you, but it is the free world that should be thanking Ukraine. Ukrainians are fighting a battle for freedom, democracy and the very notion of national sovereignty. A victory by Ukraine tells dictators everywhere that the old days, when a strong country could invade and swallow its neighbors, are not coming back. Ukraine’s loss would change everyone’s world. This is clearly not just their war. “We really fight for our common victory against this tyranny that is real life,” Zelensky said in a press conference at the White House — “and we will win.” The Ukrainian president, in his gravelly voice, was trying to convince the American people and their leaders to stick with Ukraine. He invoked the battles of American soldiers against Nazis in 1944. And he noted that Ukrainians will celebrate Christmas by candlelight – not because it’s more romantic, but because Russian attacks have left much of the country without power, heat or running water. “We do not complain,” he said, nor compare who has it harder. Ukraine just wants to receive the support it needs to continue the fight until victory. Underscoring the point, he said the soldiers fighting in the brutal battle for Bakhmut asked him to give their battle flag – a flag of Ukraine signed by its defenders – as a gift to the U.S. Congress. Tears were shed in the House. Zelensky arrived in Washington 300 days after the start of Russia’s unprovoked invasion. It was his first international trip since the war began in February, and it came at a time when several factors could conspire to counter what has been the remarkable, ferocious resistance by the Ukrainian people with the massive support from the United States and its NATO allies. With winter bearing down and Putin’s forces using Iranian drones and other artillery to bombard crucial infrastructure, deliberately targeting civilian installations and leaving millions of Ukrainians in the cold and dark, “trying to use winter as a weapon,” in the words of President Joe Biden, “freezing people, starving people,” the suffering of Ukrainian men, women and children is worsening. Putin seeks to break what has been an indomitable will to resist. At the same time, the US House of Representatives, which has been reliably supportive of Biden’s campaign to support Ukraine, is about to change hands. Some Republicans, such as Kevin McCarthy, the likely new Speaker of the House, have expressed some reluctance to continue large-scale support for Kyiv, with McCarthy saying he wouldn’t automatically support the Biden administration’s requests for more aid. And that is happening just as Putin is believed to be planning a renewed offensive. Putin, who rules over a much larger, wealthier country, apparently still believes he can win. Zelensky revealed that he outlined a 10-point peace plan to Biden, but judging by Putin’s recent statements, Russia seems more prepared to keep up the fight than negotiate. Putin seems to be counting on the United States and NATO tiring, slackening their support for Kyiv. That’s why this speech, reminiscent of Winston Churchill’s address to Congress in December 1941, was arguably the most important one Ukraine’s leader has given since the start of the war. If Americans get tired of supporting Ukraine, if they listen to the ugly voices disparaging Zelensky, Russia could ultimately win, and the world as we know it would change. It would be a victory for autocracy and a grievous loss for democracy. If Zelensky was able to make that clear, his historic visit was a triumph.