More than 300 re-enactors will descend on the town on April 30 and May 1 for the third Pikes And Plunder festival.
In 1646 the town, a Royalist outpost during the war between the crown and parliament, was cut off by 16,000 Parliamentarian and Scottish troops.
Its fall on May 8 marked the end of the first civil war that saw the British Isles plunged into violent turmoil.
The heroism, colour and tragedy of that time will be brought back to life by the National Civil War Centre and the English Civil War Society.
As part of the re-enactment, battles featuring musketeers, pikemen and cannons will be staged at Queen’s Sconce in Sconce and Devon Park — said to be the best-preserved earthen fort from the period.
There will be a living history encampment in the grounds of Newark Castle to reveal how armies were clothed and fed.
The civil war centre will host re-enactors and produce 17th Century-style propaganda sheets, using a replica printing press.
"The settings could not be more authentic."
Carol King, of the centre, said: “It will be a spectacular couple of days for visitors with the town garrisoned by hundreds of costume-clad re-enactors.
“This will be a much bigger event than last year and the settings could not be more authentic.
“We have ordered the gunpowder, cleaned the muskets and unpacked the pikes — it’s time to decide the fate of the nation once again.”
Battles at the Queen’s Sconce will start at 2pm on both days. Living history at the castle will run from 11am to 4pm.
The civil war centre, Appletongate, will open from 10am to 5pm.
There will be drills in Newark Market Place at 11.20am on both days.