Lewis did not adequately keep in touch with them.

Bates wrote letters to Lewis's superiors accusing Lewis of profiting from a mission to return a Mandan chief to his tribe. Because of Bates' accusation, the War Department refused to reimburse Lewis for a large sum he personally advanced for the mission. When Lewis's creditors heard that Lewis would not be reimbursed for the expenses, they called in Lewis's notes, forcing him to liquidate his assets, including land he was granted