Between 1885 and 1914 US bromine producers colluded to raise prices and profits. This collusion was disrupted by price wars. Bromine price wars are compared with Green/Porter and Abreu/Pearce/Stacchetti models. Some price wars resulted from the imperfect monitoring problems which motivate these models. Several empirical implications of the APS model are borne out, but the bromine industry's price wars were generally milder than contemplated by APS. More severe price wars were part of a bargaining process, in which firms tried to force renegotiation to a new collusive equilibrium with a different distribution of rents.