French troops joined their British counterparts in the famous Changing of the Guard ceremony outside Buckingham Palace for the first time Monday, marching together in a display of solidarity between Britain and France amid the war in Ukraine. At a parallel ceremony in Paris, British soldiers wearing tall bearskin hats took part in an unprecedented joint military parade in front of the presidential Elysée Palace, as the French army choir sang the two national anthems, “God Save the King” and “La Marseillaise.” The twin events were to celebrate the 120th anniversary of the Entente Cordiale, the 1904 diplomatic agreement between...