The Crimean War (October 1853 to February 1856) was fought by the Russian Empire and an alliance of the Ottoman Empire, France, Britain and Sardinia. Russian fortifications, which included some modern advances, were tested against the latest British and French artillery. At Sevastopol, the focus of the allied effort, the Russians had planned a modern fortress but little work had been done and earthworks were rapidly constructed instead. The largest and most complex earthwork, the Great Redan, was found to be largely resistant to British bombardments and difficult to carry by assault. Only one stone casemated work, the Malakoff Tower, had been completed at the time of the allied landing and proved impervious to bombardment but was finally carried by French infantry in a "coup de main". In the Battle of Kinburn (1855), an Anglo-French fleet undertook a bombardment of the Russian fortress which guarded the mouth of the Dnieper River. The most successful weapon there was the Paixhans gun which was mounted on ironclad floating batteries. These guns were the first to be able to fire explosive shells on a low trajectory and were able to devastate the open ramparts of the forts, causing their surrender within four hours. British attempts to subdue the casemated Russian forts at Kronstadt and other fortifications in the Baltic Sea using conventional naval guns were far less successful.