Was Remarque making a statement with the ironic way he kills off the characters of kat and Paul- veteran soldiers who survive many terrible fights but end up dying anyway when they aren't in battle?

Yes, Erich Maria Remarque uses the ironic deaths of Kat and Paul to highlight the senselessness and unpredictability of war. Their survival through numerous battles only to die in moments of peace underscores the idea that the true horrors of war extend beyond the battlefield. This irony emphasizes the fragility of life and the pervasive trauma experienced by soldiers, ultimately critiquing the romanticized notions of heroism and glory in warfare.