Complex sentence: Porco's best friend and fellow fighter Bellini had married Gina, and immediately after he and Porco had returned to the skies, where their seaplanes were attacked by an Austrian squadron.
Split into simpler sentences: Porco's best friend and fellow fighter Bellini had married Gina. Immediately after he and Porco had returned to the skies, their seaplanes were attacked by an Austrian squadron.