Erfworld 66: page 60

[Vreejack]

By then, the air cover will be fully back in place over the column (unless Parson manages to take out Ansom's flyers), making dwagon raids much riskier.

Yes, the air cover will return, but that is one area where Stanley's forces are not hopelessly out-classed. Ansom will have to spread his defenders about evenly, but Parson can focus on one hex at a time and perhaps eliminate both the siege and the air power---something he cannot really do against the enormous bulk of land forces because of the length of time required.

If Ansom keeps his air and siege units scattered within the column then Parson will destroy them all piecemeal. If Ansom masses all his air and siege units in one hex then Parson might be able to find some other undefended target to destroy, though few targets would be as important as the siege.

When Ansom reaches GK the dwagons will be able to rape targets of opportunity with impunity many times over each turn. Ansom will find counter-attacking almost impossible.

Seriously, with the dwagons on your side a competent strategist should never have lost a single city never mind ten (or whatever).