Expeditions are large Convoys going into the Ashen Wastes. Made up of multiple carriages filled with tools and supplies, lead by horses. They are lead by workers and guarded by the Ashen Vanguard units fulfilling their respective roles.
Expeditions into the Ashen Wastes are always ongoing, with the Ashen Vanguard rotating units whenever the convoy returns with materials and minerals.
The Expeditions rarely fail but when they do, it's felt by the entire Bastion. With temporary shortages of rare and vital minerals the city has to rely on limited stockpiles and make up the loss somehow - not only the material loss but the personnel loss, with the Ashen Vanguard being some of the best warriors the city has to offer.