The Trenchworks and other Field Fortifications gave special bonuses to the defenders. Heavy cover of course, no automatic hits on ones, standing up and going into full cover doesn't count as moving (only for handheld weapons like rifles), and most importantly round all fractions down. In GASLIGHT fractions matter. A Shoot of 7, goes to a Shoot of 3.5 at long range. Since you have to roll under the Shoot to hit, you would have to roll a 3 or less. With this rule the shoot would go to a 3, which means you would have to roll a 1 or a 2 to hit.
To balance these bonuses I gave the attackers triple the manpower (6 squads to 2) and four Landships to two "cannons". Three to one is usually considered the minimum odds for attacking a prepared defensive position.
On the Union side they had a section of trench, a nearly complete squad was about to overrun the Electrocannon, more troops were coming up, and a fight was going on at the heavy cannon emplacement.
On the Rebel side Colonel Cornpone was dead, Lt. Jackson was dead, they were down to two units of green troops, and both timberclad landships had broken down (but could still shoot)'[
A minor Union Victory