Benedict Cumberbatch has said filming the battle scenes for The Hollow Crown: The Wars Of The Roses was "brutal".
The Sherlock star, 39, plays Richard III in the concluding part of the BBC Two adaptations of Shakespeare's history plays.
The first series of The Hollow Crown, broadcast in 2012, comprised Richard II, Henry IV Parts 1 & 2, and Henry V, with Ben Whishaw winning a Bafta for Richard II.
The Hollow Crown: The Wars Of The Roses also features the very best of British talent and covers Henry VI Parts 1 & 2, and Richard III.
Viewers can expect to see bloody recreations of the battles over the throne of England between the House of Lancaster and the House of York, two branches descended from Edward III.
Benedict admitted training for the Shakespearean epic was "tough".
"We were carrying around weapons of steel and aluminium, which were props but could still do a great deal of damage," he said.
"We were fighting in fields and in rivers with water literally up to our chests. It was brutal. The broadsword as a weapon could crack your skull open with just a glancing blow."
He added: "It really is such a barbarous way to go about winning power. I'm in awe of it. The training was tough - all of us would come away from training looking shell-shocked and pale."
Benedict heads an impressive ensemble cast who are dramatising the lives of key historical figures over the next three weeks.
Theatre director Dominic Cooke is at the helm for all three films.
Viewers will see Dame Judi Dench as the Duchess of York, Downton Abbey's Hugh Bonneville portraying the Duke of Gloucester, Undercover's Sophie Okonedo as Queen Margaret of Anjou and Being Julia's Tom Sturridge in his Shakespearean debut as King Henry VI.
The line-up also includes Line Of Duty duo Keeley Hawes as Queen Elizabeth and Adrian Dunbar as Plantagenet.
Dame Judi, playing opposite Benedict as his screen mother, jokingly referred to her character as an "old bag".
She paid tribute to the star who won plaudits for his portrayal of Alan Turing in The Imitation Game. "He's a terrific actor and he did the most spectacular reading," she said.
"He'd just come back from the Toronto Film Festival the night before, after doing all those crazy junket interviews, walked in and then read the whole of the Henry VI plays followed by Richard III."
The 81-year-old added: "He has that ability not to take himself too seriously, as well as being a terrific actor."
Saturday's first instalment opens with Henry VI Part I with Hugh, Sophie and Adrian, alongside Sir Michael Gambon as Mortimer.
The Downton Abbey star pointed to his character's pivotal role in maintaining peace.
"It is Gloucester's death that unleashes the Wars Of The Roses," Hugh said. "The stability he represented was a certain kind of peace. You take out the central pillar of any society, then you create a vacuum. I'm not making grand claims for this, but you see it in Yemen, or Iraq, or Syria."
On the same theme, he stated: "In the play, you see the dukes piling in and chaos begins. This is the heart of the Wars Of The Roses."
Asked if The Hollow Crown: The Wars Of The Roses will introduce Shakespeare to new audiences, Hugh said he was sure it would.
"People shy away from these plays, but our version is very accessible," he said.
The Hollow Crown: The War Of The Roses, Henry VI Part 1 is broadcast on May 7 on BBC Two.