expeditionary

Of or pertaining to an expedition.

Intended for military operations abroad.

an expeditionary force

One who goes on expeditions, especially one who is a member of an expeditionary military force.

[...] turned out in its best attire to receive the Brazilian expeditionaries and the group of soldiers representing the gallant U.S. 10th Mountain Division.

He who had been left for dead, rose again in three days to become the leader of the expeditionaries and, in a very real way (albeit not exclusively), [...]. Antonio “ Tintin” Vizintin was brave and strong, qualities that made him a good expeditionary.