question on building field fortifications

[Trapper John]

In a PBEM campaign, I haven't been able to get the "build fortification" button to light. I've assembled what I believe to be the required units in a city under Federal control -- 4 batteries of cannon, 2 separate supply units, plus an engineer unit and infantry led by an activated leader. I've also tried outside/adjacent to the city. Not sure what else is necessary. Would appreciate any advice, thanks

[Rafiki]

Hi Trapper John, and welcome to the forums

Are you sure you fulfill all of the following?

• You must have 2 supply wagon units and 4 artillery units gathered in a region. Note: The artillery units need not be of the same type.
• The units cannot be depleted and must have at least 50% strength.
• The units cannot be in a stack led by an inactive general.
• You must have at least 51% military control of the region in question.
• There must be a city (of any level) in the region.

(You say you fulfill some of these, but what about the 2nd and 4th items?)