Present and anticipated military missions require highly trained and capable military personnel. Military personnel have to be well prepared to effectively and efficiently use state-of-the-art technology under highly complex battlefield conditions. A number of factors are influencing training policies, procedures and technologies. An important factor is the need for units to deploy. This places them in locations where they do not have the facilities and infrastructure needed to optimally plan and rehearse complex missions. Recent advances in computer and display technologies make embedding training and embedded virtual simulation in highly mobile military hardware both practical and effective. Embedded training is a well-known concept, which tightly integrates training functionality into operational equipment. It allows military personnel to train and rehearse while deployed to an operational area. Embedding training allows skills to be maintained and developed close to the battlefield or during transit. In the past, embedded training has been successfully applied by armed forces primarily for large computer controlled systems such as air defense, and ships. The recent development in areas like Virtual Reality (VR) and Augmented Reality (AR), technologies for virtual simulation and intelligent tutoring systems significantly enlarges the area of application to ground and air forces. The human-centered design and integration of embedded virtual simulation (EVS) technologies covers a broad spectrum, which includes questions in operational user requirements, in training management as well as innovative technologies for the human interface and a possible application of intelligent agents. This paper will present some new successful applications of embedded virtual simulation in ground and air applications. It will refer to relevant aspects of the topic from a training perspective and summarize the results that were achieved during the three year of operation of a NATO research study group (HFM-165) on enhancing human effectiveness though embedded virtual simulation. Based on these findings future directions towards the future development of EVS will be presented.