The first test of the summer didn't start too well for the hosts as they had a very shaky morning at the home of cricket, losing four early wickets, but Root showed his class in his first test as captain to put the hosts in a great position ahead of day two.
Ben Stokes, who made 56, and Moeen Ali, who finished the day 61 not out also made great contributions after Vernon Philander had done the early damage for the Proteas.
The Proteas started brilliantly with the ball as the hosts got off to a shaky start
The day started well for Root as he won his first toss as captain and chose to bat first on a beautiful sunny day at the home of cricket.
The problem for the hosts though was the fact that Philander started wonderfully with the ball removing Alastair Cook for three and Keaton Jennings for eight to leave the hosts on 17-2 and struggling.
Gary Ballance, returning to the side, tried to prove his worth to the side and looked good at the crease until Morne Morkel removed him for 20 after trapping him LBW.
The Proteas therefore had their tails up and they managed to get yet another important wicket before lunch when Philander trapped the in-form Jonny Bairstow LBW for 10.
Therefore, at lunch, the hosts were reduced to 82-4 with Root still at the crease on 33 with Stokes just starting his innings and looking to provide support to his captain after the short break.
Root and Stokes led a strong England fightback after lunch
After lunch, it was a totally different story to the morning as the hosts went through the whole second session without losing a wicket much to the help of costly mistakes from the Proteas.
Root and Stokes showed their class as both batsmen went passed fifty as the pair put on 100 runs in the session without being dismissed.
Stokes though received a life before getting to his fifty when he was bowled by Morkel but the big fast bowler overstepped much to the disbelief of the tourists.
Therefore, at tea, the hosts reached 182-4 with Root 79 not out and Stokes 52 not out with the pair having a partnership of 106 unbroken.
Root reached his century in the final session of the day as the hosts ended the day on 357-5
After tea, both Stokes and Root wanted to carry on from were they left off but their partnership was finally broken when Kagiso Rabada removed Stokes for 56 to leave the score on 190-5.
That was as good as it got for the Proteas in the final session of the day though and the hosts didn't lose any more wickets as Moeen Ali joined Root at the crease.
The pair put on a unbeaten century partnership with Root reaching his century in his first test as captain while Ali provided fantastic support by passing his half-century.
Therefore at the end of the play, the hosts reached 357-5 with Root unbeaten on 184 and Ali unbeaten on 61 with the pair looking to kick on during day two.