You might like to look at Chapter 22, which is when we are given our first introduction to the Reverend James Smith in this excellent novel. What is important to realise is that the Reverend Smith in many ways functions as a foil for his predecessor, as he is defined primarily by their different approach to their work of converting the heathen masses in Okoknkwo's tribe. Consider what this quote says about him:
Mr. Brown's successor was the Reverend James Smith, and he was a different kind of man. He condemned openly mr. Brown's policy of compromise and accommodation. He saw things as black and white. And black was evil. He saw the world as a battlefield in which the children of light were locked in mortal conflict with the sons of darkness.
We can see therefore that the Reverend James Smith is described as being much more confrontational and antagonistic than his predecessor. This of course is used by Achebe to foreshadow some of the difficulties that Okonkwo's tribe will face. Compared to his predecessor's policy of accommodation and compromise, this character is clearly much more determined to engage in what he calls a "battle," which will result in sadness and grief to many.