Complex sentence: She prepared for the bloody invasion of the Japanese home islands from 26 June until 15 August 1945, with exercises at Leyte but with the surrender of Japan on 15 August 1945, the training exercises were canceled.
Split into simpler sentences: She prepared for the bloody invasion of the Japanese home islands from 26 June until 15 August 1945, with exercises at Leyte. But with the surrender of Japan on 15 August 1945, the training exercises were canceled.