A new approach to guiding a swarm of missiles using an on-line evolutionary algorithm to optimise the flight paths is introduced. The missiles are flown via intermediate points which are adjusted dynamically by the evolutionary algorithm, then towards the point of impact with the target, thus altering the trajectory shape. Evolutionary algorithms are robust global optimisation techniques and are able to cope well with noise and uncertainty. This framework can be used to generate optimal flight profiles that satisfy multiple objectives and constraints. Example trajectories are presented for a multiple missile scenario using a highly non-linear model of a boost-glide missile.