Following that assignment, he spent several years surveying routes for railroads, most significantly the path of the Northern Pacific across the Cascades. McClellan’s job was to select an appropriate route for the planned transcontinental railroad. He began to display a cautious tendency when he refused the governor's order to lead a party through a pass in winter conditions, relying on faulty intelligence about the depth of snow pack in that area. In so doing, he missed three greatly superior passes in the near vicinity. In 1855 McClellan joined the cavalry and was assigned as an official observer to the Crimean War. During that time he began to design the “McClellan saddle" by modifying European models. In 1857, McClellan resigned from the service and became the head of engineering for the Illinois Central Railroad. He contributed greatly in expanding the Illinois Central toward New Orleans and helping the Ohio and Mississippi recover from the Panic of 1857. In 1860, McClellan was appointed president of the Ohio & Mississippi
Following that assignment, he spent several years surveying routes for railroads, most significantly the path of the Northern Pacific across the Cascades. McClellan’s job was to select an appropriate route for the planned transcontinental railroad. He began to display a cautious tendency when he refused the governor's order to lead a party through a pass in winter conditions, relying on faulty intelligence about the depth of snow pack in that area. In so doing, he missed three greatly superior passes in the near vicinity. In 1855 McClellan joined the cavalry and was assigned as an official observer to the Crimean War. During that time he began to design the “McClellan saddle" by modifying European models. In 1857, McClellan resigned from the service and became the head of engineering for the Illinois Central Railroad. He contributed greatly in expanding the Illinois Central toward New Orleans and helping the Ohio and Mississippi recover from the Panic of 1857. In 1860, McClellan was appointed president of the Ohio & Mississippi