Poland was Ukraine’s staunchest ally. Why is it now turning into a bitter rival? | Karolina Wigura and Jarosław Kuisz

War fatigue has set in - and nationalist populists are stoking cross-border enmity in a brutal campaign for re-election

An extraordinary rally in Warsaw last Sunday drew crowds of up to 800,000 opposition supporters, many waving Polish and EU flags, on to the streets of the capital. The prevailing atmosphere was one of peaceful concern for the fate of the country. As one of the biggest demonstrations in Poland's recent history, it was a stunning show of support for the opposition Civic Coalition and its leader, former prime minister Donald Tusk, as he prepares to challenge the rightwing populist governing party Law and Justice in elections on 15 October.

But despite the success of the march, and all it symbolised, Poland's authoritarian trajectory is stronger than it has ever been. For the past eight years, the government of an EU member state has been in the grip of unremitting populism. Ever more institutional elements of the liberal democratic system have been stripped away, while independent media have been targeted and minority rights significantly weakened.