A system termed VIGILANT+ is outlined, which utilises situation awareness for the purposes of enabling distributed, autonomic, sensor management, so that savings on consumption of network resources can be achieved. VIGILANT+ is a novel proposition allowing deployed, unattended, wireless sensor nodes to self-organise into dynamic groups and self-manage their transmissions efficiently, according to a current common mission objective. First, a distributed situation assessment system named PORTENT model detects and characterises potential situations occurring within an uncertain environment, using the metric, quality of surveillance information. Secondly, a Bayesian belief network is utilised to understand and analyse the significance associated with the potential situation, primarily to enable deployed sensors to self-organise and assign themselves to mission objectives autonomously. Thirdly, a system is introduced for distributed autonomic transmission control, which enables the efficient management of sensor network resource consumption. Simulations have been undertaken to verify the integrated VIGILANT+ concepts and to demonstrate the effectiveness of the proposed approach in improving network efficiency, without compromising the presentation of mission surveillance utility.