Charles Powell Leslie II came to national attention 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. This work covers his landed estate business in the years from the Action of Union to the 1840s famine and reconstructs the landlord-tenant relationship on his estates. It analyzes the changes which took place within the local community living on these north County Monaghan estates, describing how their livelihoods and their living conditions changed during these years. The study shows how this local community and Leslie’s estate business suffered severely from the post-Napoleonic war recession and how this situation was exacerbated by the famine of 1817. It shows Leslie’s response to this recession and how he managed his estate business so that it did not drift towards bankruptcy.