Just a rough drawing of the area about Dybbøl, on a screenshot from google maps.
The Danish lines in April 1864 (in red) had a total of 10 redoubts (only marked some of them), with a lot of heavy artillery. (including a good number of smoothbore 84 pounders... that could fire cannister out to 600 yards and shells to 1000)
In font of the fortifications. Wire fences and spiky farming equipment force the attackers into a killzone where cannister and infantry fire would cut them down.
It was a very very strong position... if it been in 1860 before the Prussians started having rifled siege artillery.
The Prussians places batteries of rifled siege artillery in the south.
And then systematically shot the Danish defenses to bits.
At that range the Danish 84 pounder would expect to hit a target the size of a ship of the line 0,5% of the time.
(hit the hull that is)
The Prussians could put close to 100% of their rounds within a Danish redoubts.
This was done at a range of 2,5-3km.
The white line to redoubt IV is 2,71km.
In an attempt to counter this the guns in redoubt II was replaced with rifled field guns... this di help draw a lot of Prussian fire.. allowing the others to be repaired at night.
The larger redoubt had blockhouses build in very heavy timber. they where immune to roundshots from smoothbores at that range.
But 30 pounder shell flew in over the walls of the redoubt, hit the side of the blockhouse in one of the redoubt and detonated inside...
(so artillerymen started to take cover in the ammunition bunkers...since they where made of concrete)
During this they dug parallels and then on the 18th of April stormed the position.
They started by 4 hours of heavy bombardment, then stopped and then the artillery shifted to hit the area behind the Danish front lines. Basically interdicting the frontlines. (Something that would be very normal tactics during the great war.)
This actually had the effect that the Danish reserve, didn't know there attack was happening until way to late because the noise of the shelling blocked out the Nosie of the attack. The Danish system of buglers to warn of an attack failed... no one knows why, but some of the buglers assign to the system died, so likely a random shell removed a link in the chain.
Note it is just a rough drawing.
for the official map made by the Danish Engineers look at this:
http://military-history-denmark.dk/wp-content/uploads/2020/03/Dybboel_ingenieurkommandoen.jpg