The Ottoman Army was the army of the Ottoman Empire after the country was reorganized along modern western European lines during the Tanzimat modernization period. It operated during the decline and dissolution of the empire, which roughly occurred between 1861 (though some sources date back to 1842) and 1918, the end of World War I for the Ottomans. The Crimean War was the first war effort in which the modern army took part, proving itself as a decent force. The last reorganization occurred during the Second Constitutional Era.