For what crime was Harman Blennerhassett indicted due to his plot with Aaron Burr?

Harman Blennerhassett was indicted for treason due to his involvement in a plot with Aaron Burr. This plot was centered around the establishment of a separate territory in the western part of the United States, which was considered an act of rebellion against the federal government. Treason is defined as acts that betray one’s allegiance to their country, and in this case, Blennerhassett's actions, in collaboration with Burr, were viewed as a direct challenge to the authority of the United States.

The other options, while related to criminal activities, do not accurately capture the nature of the accusations against Blennerhassett. Conspiracy involves planning an unlawful act, espionage typically pertains to spying or gathering secret information, and forgery relates to the falsification of documents. None of these categories encompass the serious implications of treason, which directly addresses the undermining of the nation's sovereignty.