Complex sentence: When Axel Jensen arrived in Oslo, he met his old friend, the writer Olav Angell, and Jensen became the chairman in a project which later developed into the Oslo International Poetry Festival (OIPF), occuring in 1985 and 1986.
Split into simpler sentences: When Axel Jensen arrived in Oslo, he met his old friend, the writer Olav Angell. The plan was soon made into action, and Jensen became the front figure in a project which later developed into the Oslo International Poetry Festival (OIPF), occuring in 1985 and 1986.