Ever since the inception of the idea of collaborating the enterprise systems, the need of an Enterprise Service Bus (ESB) has been a relentless need of the market, the bigger the systems get after collaboration the failures of the ESB's was inevitable. Things moved to more gravity when the bulkiest of the systems like Defense architectures came into picture, with the advent of this not of the efficiency but also the factors like stability, reliability, resource utilization were also of pivotal importance. This paper reviews a critical and comparative analysis of the current ESB's keeping in view the C4I System as a base, so as to ascertain which ESB fulfills the requirements of the system of systems. In comparison we try to analyze Mule ESB, GlassFish ESB and Fuse ESB with respect to interoperability. This study demonstrates that Mule is more feasible to C4I systems because it is simple, easy to integrate, no adopter requirement and flexible.