Charles Powell Leslie II came to national attention on a number of occasions, most notably as colonel of the Monaghan militia during the suppression of the 1798 rebellion in Down and Antrim, and as the opponent whom the Catholic Association defeated in the 1826 County Monaghan election. Daniel O'Connellndescribed him as '...one of the most uncompromising enemies of his Catholic country men...' Conversely, his protestant opponents were attacking his loyalty to the protestant cause, because of his ancestors' links to the Jacobites. This study examines Leslie's management of his landed estate business in the years from the Act of Union to the 1840s famine and reconstructs the landlord-tenant relationship on his estates. It analyses the changes which took place within the local community living on the north County Monaghan estates, derscribing how their livelihoods and their living conditions changed during these years.