The European Union is the West’s last line of defense. The United States has historically been the world’s anchor of republican ideals, but President Trump has abandoned the role, openly admiring strongmen like Vladimir Putin of Russia. As the temptations of nationalist populism spread, Europe has responsibility for holding down the Western fort. The primary battle right now is over Poland, which is deepening its descent into illiberalism. The European Union needs to take a firm stand in defense of Western values.