The folktale about the tortoise and the birds in chapter 11 of Things Fall Apart can be seen as foreshadowing what major event?

Ekwefi tells Ezinwa an old story from Igbo folklore. In the story, some birds are about to enjoy a feast in the sky. A greedy tortoise wants to get a piece of the action, so he asks the birds to make him some wings that will enable him to fly up to the sky and partake in the sumptuous banquet. When he arrives at the feast, the tortoise asks the birds another favor. He wants them to call him "All of you." The reason for this soon becomes clear. For when it's time to eat, the tortoise asks his hosts who the feast is for. "All of you" is the reply, at which the greedy tortoise proceeds to eat everything in sight.
The birds are angry at being duped, so they remove the tortoise's wings, leaving him stranded. The tortoise has no choice but to prepare for a safe landing, so he persuades the parrot to tell his wife to put soft objects on the ground to break his fall. The sly parrot, however, tells the tortoise's wife to put hard objects down, instead. When the tortoise falls, he breaks his shell, which is then put back together again by a medicine man.
The animal fable foreshadows the arrival of colonialism to Umuofia. The colonialists are represented in the story by the greedy tortoise, and the indigenous people by the birds. The birds use two strategies to defeat the tortoise, and these provide a valuable lesson for the villagers in their anti-colonial struggle. The first involves standing together and refusing to give the tortoise what he wants—wings. Just as the tortoise can do nothing without the wings, so the colonialists cannot control the village if the local people refuse to cooperate with them.
The second strategy involves tricking the tortoise. This is what the sly parrot does when he passes on a false message to the tortoise's wife. In the long, hard struggle ahead, the people of Umuofia must also use cunning and guile to wear down their colonial oppressors, making it harder for them to rule effectively.