Complexity is ever increasing in current military operations, not only because of its required coalition composition but also because missions are more often performed in a comprehensive environment with many different actors, including military, civil and police organisations. In order to prepare the warfighter for these complex missions, advanced training, in which the warfighters are immersed in such complex environments, is required. (Distributed) simulation has been recognized by NATO as a solution to support this type of training and the concept of “Mission Training through Distributed Simulation” (MTDS) is currently developed by several nations under the umbrella of the NATO Modelling and Simulation Group.. The Netherlands MoD has identified the need for MTDS capabilities and initiated an MTDS research programme in 2017. Developing a so-called Reference Architecture for MTDS is one of the main objectives of this research programme. The CAX exercise VIKING-18 was selected as a use-case to investigate technical solutions that can be used to define generic elements of this MTDS Reference Architecture. This paper presents the VIKING-18 exercise, its objectives and the MTDS Reference Architecture elements that have been derived from this exercise. These elements provide services for the simulation of realistic maritime vessel traffic including transmission of ’Automatic Identification System (AIS)’ messages, and services for the simulation and control of land units using the “Low Level Battle Management Language (LLBML)” standard. The work was performed in a collaboration between TNO Defence Research (NLD), Pitch Technologies (SWE), and the Swedish Armed Forces (SWAF) Joint training centre.