  Conquerors of old (like, e.g., Alexander the Great or Ceasar) had to solve
the following deployment problem. Sufficiently strong units had to be stationed
at locations of strategic importance, and the moving forces had to be strong
enough to advance to the next location. To the best of our knowledge we are the
first to consider the (off-line) graph version of this problem. While being
NP-hard for general graphs, for trees the minimum number of agents and an
optimal deployment can be computed in optimal polynomial time. Moreover, the
optimal solution for the minimum spanning tree of an arbitrary graph G results
in a 2-approximation of the optimal solution for G.
