Convoys allow Bomber Units (not Fighters) to transport Ground Units to a drop-off destination, and optionally “fly on” to a different space, known as the fly-on destination. The drop-off destination may be one or two spaces away from the space being ordered. The total flight may be up to three spaces, or it may return to the original space via a drop-off target that is up to two spaces away. The entire flight must take place in spaces that are not blocked (hostile or contested).
Convoys, like all Manoeuvres, are optional, and the number of Units sent is also optional. A Bomber Unit may carry zero or more Units on the Convoy. The Bomber may choose not to continue to the fly-on destination. Each leg of a Convoy must satisfy all of the same requirements that apply to Moves, and must pass over unblocked spaces throughout the flight. If the proposed flightpath is blocked, the Convoy can be shortened to land on one of the intervening spaces, depositing its Ground Units at the new destination, provided that the emergency landing space is not blocked.
Both legs of a Convoy flight enjoy flight-path flexibility, as described for Moves. The fly-on leg is processed as a new Move from the drop-off point to the original target, but with a reduced movement budget. It does not have to include a visit to the originally targeted drop-off point. The total flight including the fly-on must still satisfy the usual distance limits (a 3-space flight in total or 2 spaces and return). The fly-on leg is executed after the troops are dropped off, and opposing Location Cards may be declared after the troops have been dropped off. The fly-on is optional, and any number of Air Units may choose to stay at the drop-off zone instead. If the fly-on leg has a movement budget of 2 spaces, it enjoys the same flight-path flexibility as a normal Move, and it may be shortened to avoid an obstruction.
Ground Units are never the recipient of a Convoy order, and therefore they may respond to their own order prior to being Convoyed. For instance, a Ground Unit may March or Move to the start of a Convoy and then join the Convoy. A Ground Unit could be Convoyed multiple times. This does not violate the general principle that each Unit may only respond to one order, because the Convoy order is not directed at the Ground Unit.
A Fighter Unit may respond to a Convoy order by accompanying a Convoy to the drop-off target or the fly-on destination but it may not March or Move to the start of a Convoy and then join the Convoy (because that would require the Fighter to respond to two Air Orders). A Fighter Unit may not fly in response to a Convoy Order unless it is accompanying a Bomber Unit.