Manon des Sources

Following the events of Jean de Florette, Manon, the daughter of Jean, is living in the countryside of Provence near Les Romarins, the farm that her father once owned. She has taken up residence with an elderly Piedmontese squatter couple who teach her to live off the land, tending to a herd of goats and hunting for birds and rabbits. Ugolin Soubeyran, also called Galinette (only by his uncle CÃ©sar), has begun a successful business growing carnations at Les Romarins with his uncle, CÃ©sar Soubeyranâalso known as Papetâthanks to the water provided by the spring there.
After seeing her bathe nude in the mountains, Ugolin develops an interest in Manon. When he approaches her, she seems disgusted by his vileness and almost certainly by the memory of his involvement in her father's downfall. But Ugolin's interest in Manon becomes obsessive, culminating in sewing a ribbon from her hair onto his chest. At the same time, Manon becomes interested in Bernard, a handsome and educated schoolteacher recently arrived in the village. As a small child, Manon had suffered the loss of her father, who died from a blow to the head while using explosives in an attempt to find the water source. CÃ©sar and Ugolin then bought the farm cheaply from his widowâManon's motherâand unblocked the spring. Manon witnessed this as a child. The two men profited directly from his death.
When she overhears two villagers talking about it, Manon realises that many in the village knew of the crime but had remained silent, for the Soubeyran family was locally important. While searching for a goat that fell into a crevice above the village, Manon finds the underground source of the spring that supplies water to the local farms and village. To take her revenge on both the Soubeyrans and the villagers, who knew but did nothing, she stops the flow of water using the iron-oxide clay and rocks found nearby.
The villagers quickly become desperate for water to feed their crops and run their businesses. They come to believe that the water flow had been stopped by some Providence to punish the injustice committed against Jean. Manon publicly accuses CÃ©sar and Ugolin, and the villagers admit their own complicity in the persecution of Jean. They had never accepted him, as he was an outsider and was physically deformed. CÃ©sar tries to evade the accusations, but an eye-witness, a poacher who was trespassing on the vacant property at the time, steps forward to confirm the crime, shaming both CÃ©sar and Ugolin. Ugolin makes a desperate attempt to ask Manon for her hand in marriage, but she rejects him. The Soubeyrans flee in disgrace. Rejected by Manon, Ugolin commits suicide by hanging himself from a tree, apparently ending the Soubeyran line.
The villagers appeal to Manon to take part in a religious procession to the village's fountain, hoping that acknowledging the injustice will restore the flow of water to the village. With the assistance of Bernard, Manon unblocks the spring in advance, and the water arrives at the village at the moment that the procession reaches the fountain. Manon marries Bernard. She is last seen very pregnant and leaving a church service on Christmas Eve with her husband.
Meanwhile, CÃ©sar has been broken by his nephew's suicide. Delphine, an old acquaintance of his, returns to the village and tells him that Florette, his sweetheart from that period, had written to him to tell him she was carrying their child. Receiving no reply from him, she had tried to abort it. Florette left the village, married a blacksmith from nearby CrÃ©spin, and the child was born alive but a hunchback.
CÃ©sar, away on military service in Africa, never received her letter and did not know that she had given birth to his child. In a cruel twist of fate, Jean, the man he drove to desperation without having met him, was the son he had always wanted. Devastated, and lacking the will to live any longer, CÃ©sar dies quietly in his sleep. In a letter he leaves his property to Manon, whom he recognises as his natural granddaughter and the last of the Soubeyrans.

Question: How did Manon's father die?
Answer: A blow to the head