Next generation tactical military network will be based on mobile ad hoc networks (MANET). These networks require efficient spatial channel reuse in order to provide high spectral efficiency and this requires as well a stable network structure as an efficient channel assignment optimization method. In this paper ant colony optimization (ACO) and imperialist competitive algorithm (ICA) are merged in the cognitive manager for the combined clustering and channel assignment problem in a clustered based MANET. Ant colony optimization is used to choose the cluster head in an as advantageous way as possible. The used multi-objective function is defined to maximize the stability and scalability, minimize the number of clusters, and minimizing interference power in between clusters. The imperialist competitive algorithm is applied for solving the channel assignment problem. In this case the multi-objective function minimizes interference and maximizes the spectral efficiency.