Another nice strategy is to have 2 flamethrowers going through the top of the field. This way they will scorch the enemy before they can react to throwers. Downside is that you have to keep track of your flamies unless you want them to get a warm hug.
Try 5 mortars and anti-air gun + few soldiers to keep pinned down and for close protection.
Remeber to have at least one officer to concentrate fire on enemy mortars though. Seems to work quite nicely
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