Flashbacks add dimension to Achebe's writing. The flashbacks reveal Okonkwo's images of his father. The flashbacks help develop the character of Unoka. The reader can get a visual image of Unoka. Likewise, the reader can understand the relationship between Okonkwo and his father. It is easy to see why Okonkwo fears becoming like his father. It is easy to see why Okonkwo despises the father he knew as lazy and dishonorable.
Through the flashbacks, readers can understand emotional and physical characteristics of characters who are introduced. Unoka enjoys the party life; drinking and playing his flute are things he enjoys. Without the flashbacks, the reader would not have clear images into the character Unoka. Flashbacks give the reader an opportunity to see into Okonkwo's past. The reader can imagine how disturbed Okonkwo is because of his father's passive, lazy actions when Okonkwo was just a young boy.
Using a falshback helps the author insert information that cannot be revealed in any other way. It is a technique or tool that moves the story forward:
The purpose of the flashback is simple: it is a technique that bridges time, place and action to reveal information about the character, or move the story forward.