What mistake did major long make that resulted in a failed expedition?

Major Stephen H. Long's expedition, which took place in 1819-1820, failed primarily due to his underestimation of the harsh conditions and logistical challenges of the Great Plains. He relied heavily on a limited supply of provisions and misjudged the capabilities of his team and equipment, leading to severe shortages and poor navigation. Additionally, Long's lack of adequate preparation for the region's climate and geography contributed to the expedition's struggles and eventual failure to achieve its objectives.