This paper analyses the success of the Lebanese banking system during the Lebanese civil war, which lasted from 1975 until 1989. As the rest of the economy plunged into recession due to intense warfare and governmental collapse, the bankers and their clients continued to cooperate across battle lines in the loaning business. The argument of the paper is that the linkage of social and economic games and the importance of reputation in business created incentives for bankers and businessmen to cooperate in the Prisoner’s Dilemma game of lending and borrowing. I challenge the theoretical perspective that cooperation is not possible in a hostile environment in which formal enforcement institutions are inoperative. This case study provides evidence of cooperation under extremely adverse conditions.