We are definitely missing something here. From this chapter it is fairly obvious that there is a letter that was written which chastised the Corinthians, but it is obviously not the first letter to the church in Corinth which we have. Paul tells the church in vs.8 that he was sorry if his letter caused sorrow within the church, but only to the extent that it caused sorrow, not because he was wrong to write the letter. In fact, it was good that he wrote the letter, he states, because it lit a fire under them to do something to get themselves out of whatever the situation was. He alludes to the situation in vs.12 where he states that there was someone who committed a wrong and someone who was wronged. At least this we know, but nothing more.
Titus is mentioned here in this chapter. If you want to know more about Titus feel free to read the miniscule letter, only 3 short chapters, where you can read more about this person of faith. He is said to have brought about great peace to the community of Corinth after delivering a letter that condemned some of the actions of the Corinthian church. This is what is mentioned in vs.8. As a result of Titus, II Corinthians is thought to have been written. So Titus is not an insignificant person. He is beloved by Paul who brought him to the Jerusalem Assembly in Acts 15 and then argues that while some should be circumcised in order to represent the Gospel, such as Timothy, Titus did not need to succumb to that procedure.
It is an interesting chapter because it reminds us that there is a lot of history involved in the life of Paul which we don’t know just from reading the Bible. In fact, much of it may be lost.