rolling stock were crucial in maintaining the sphere of influence. Railroads were the fastest and cheapest way of moving large number of troops, and most battles during this era were fought within a short distance of railways. In 1925, it was estimated that 70% of the locomotives on the railway lines connecting Wuhan and Beijing, and 50% of the locomotives on the lines connecting Beijing and Mukden were being used for mobilizing troops and supplies. Armoured trains, full of machine guns and artillery, offered fire support for troops going into battle. The constant fighting around the railroads caused much economic harm. In 1925 at least 50% of the locomotives being used on the line connecting Nanjing and Shanghai had been destroyed, with the soldiers of one warlord using 300 freight cars as sleeping quarters, all inconveniently parked directly on the rail line. To hinder pursuit, defeated troops tore up the railroads as they retreated, causing in 1924 alone damage worth 100 million silver Mexican dollars (the Mexican silver dollar was the main currency used in China at the time). Between 1925 and 1927 fighting in eastern and southern China caused non-military railroad traffic to decline by 25%, raising the prices of goods and causing inventory to build up at warehouses. Warlord profiles Few of the warlords had any sort of ideology. Yan Xishan, the "Model Governor" of Shanxi, professed a syncretic creed that merged elements of democracy, militarism, individualism, capitalism, socialism, communism, imperialism, universalism, anarchism, and Confucian paternalism into one. A friend described Yan as "a dark-skinned, mustached man of medium height who rarely laughed and maintained an attitude of great reserve; Yan never showed his inner feelings." He kept Shanxi on a different railroad gauge from the rest of China to make it difficult to invade his province, though that tactic also hindered the export of coal and iron, the main source of Shanxi's wealth. Feng Yuxiang, the "Christian General", promoted Methodism together with a vague sort of left-leaning Chinese nationalism, which led the Soviets to support him for a time. He banned alcohol, lived simply and wore the common uniform of an infantryman to show his concern for his men. Wu Peifu, the "Philosopher General", was a mandarin who passed the Imperial Civil Service exam, billing himself as the protector of Confucian values, usually appearing in photographs with the scholar's brush in his hand (the scholar's brush is