Science and technology play an increasingly important role in equipping and supporting the armed forces. Mathematics is fundamental to these disciplines, providing a framework for understanding and solving the varied and complex problems faced. Mathematics and statistics are used to model military systems and scenarios. The information provided by mathematical models can be used to estimate system performance, suggest improvements or find weaknesses of real systems. This conference brings together a wide variety of mathematical methods with defence and security applications. The conference programme will include keynote speakers, contributed presentations and poster sessions as well as refreshment breaks for informal discussions. It is intended for mathematicians, scientists and engineers from industry and academia, as well as government and military personnel who have an interest in how mathematics can be applied to defence problems. This will be the third Mathematics in Defence conference; the first two conferences, held in 2009 and 2011, each attracted over 100 delegates from a range of organisations including QinetiQ, Dstl, BAE Systems, Thales, Rolls Royce, the IMA, the MoD, academic establishments and international parties.