During WWI, 900 Type B were used to move troops behind the lines. In addition a small number were also converted as mobile pigeon lofts to transport the communication pigeons (and other birds) used to relay messages from the front line back to headquarters. The buses were converted to carry between 60 and 75 birds in specially installed cages on both decks with birds being released through cut-outs on the upper deck. Converted Type Bs remained in service until the end of the conflict.