Ukraine’s President Volodymyr Zelensky made an unannounced visit to the front-line city of Bakhmut on Tuesday, rallying troops on the country’s deadliest battlefield as Russia intensifies efforts to seize it.

Russian forces, including the Wagner private military company, have been fighting for the town for nearly six months. Both sides have poured troops, tanks and artillery into the city, where brutal trench warfare has drawn comparisons to World War I.