1. The Escape of Sirius Black: The most immediate and obvious conflict is the escape of Sirius Black, a dangerous prisoner accused of murdering twelve people and being Voldemort's right-hand man. This threat hangs over the entire story, as everyone at Hogwarts, including Harry, fears Black's potential return to wreak havoc.
2. The Threat of the Dementors: The introduction of Dementors, soul-sucking guards who represent fear and despair, adds another layer of external conflict. Not only are they a constant threat to the students and staff of Hogwarts, but their presence also brings up Harry's own trauma from his parents' death.
3. Harry's Growing Understanding of his Past: Harry's journey to uncover the truth about Sirius Black and his connection to his parents becomes a major external conflict. He must confront his own fears and prejudices about Black while trying to understand the complicated events that led to his escape.
4. The Struggle for Justice: The story explores the theme of justice versus vengeance. While the Ministry of Magic seeks to punish Sirius Black without a fair trial, Harry, Hermione, and Ron try to uncover the truth and ensure that the innocent are not punished.
5. The Internal Conflict Within the Ministry: There's also a subtle external conflict between the Ministry of Magic and the truth. Their obsession with maintaining control and their fear of the truth create a system that perpetuates injustice, a conflict Harry and his friends challenge throughout the story.
6. The Battle of Hogwarts: Although the story focuses on Sirius Black, the book also builds towards the final confrontation with Voldemort. This conflict is simmering in the background, with glimpses of Voldemort's influence and the growing threat he poses to the wizarding world.
It's important to note that these external conflicts often intersect with Harry's internal struggle to understand his identity and purpose. Each of these external conflicts contributes to the book's compelling narrative and adds layers of complexity to the overall story.