Southeast Missouri was where Ulysses S. Grant began his rise to prominence as a soldier. In mid-August 1861 at Ironton, Missouri, and then at Cape Girardeau, where he arrived on August 30, 1861 as a newly commissioned brigadier general of volunteers commanding the Union District of Southeast Missouri, Grant began the campaign that would help secure control of the Mississippi River. After service in Ironton and a brief assignment in Jefferson City, he was summoned to army headquarters in St. Louis on August 28, where, according to one eyewitness account, he was chosen to lead an offensive from Southeast Missouri. After assembling a staff, he traveled by steamboat to Cape Girardeau, probably lodged at the St. Charles Hotel, and ordered Union regiments from Ironton to march there for offensive operations. When those troops arrived on September 2, a dispute over rank broke out between Grant and Brigadier General Benjamin Prentiss, whose claim to seniority was rejected, and Grant's authority was upheld. Grant moved his headquarters to Cairo, Illinois, on September 4, then on September 5 organized the movement against Paducah, Kentucky, in response to the Confederate army's entry into that neutral state, and on the next day occupied the city with a small force. He returned to Cape Girardeau on September 7 to arrange the disposition of troops still stationed there. From Cairo on November 7, 1861, Grant launched his last campaign in southeast Missouri, sending Union troops to Sikeston and Bloomfield before attacking Belmont in Mississippi County, the first Civil War battle in which the future lieutenant general commanded troops in the field. He then moved on to Fort Donelson in January 1862 and later to Shiloh. During the first months of the Civil War, Cape Girardeau became one of the most fortified cities in the western theatre because its high ground overlooked the Mississippi River north of its confluence with the Ohio River. Four earthen forts and entrenchments were nearing completion by October 9, 1861, when Grant visited on an inspection tour. Their construction was supervised by Lieutenant John Wesley Powell, who later lost his right arm at Shiloh, led the 1869 expedition that explored the Grand Canyon, and became the second and most influential director of the U.S. Geological Survey.