Task: Question Answering
Input (English): Passage: When Sigurd died in 1130, Harald broke his oath. Sigurd's son Magnus was proclaimed king, but Harald also claimed the royal title, and received much support. A settlement was reached whereby Magnus and Harald would both be kings and co-rulers. Peace between them lasted until 1134, when open war broke out. In 1135 Harald succeeded in defeating and capturing Magnus in Bergen. Magnus was blinded, castrated, mutilated and imprisoned in a monastery. He was thereafter known as Magnus the Blind. At about the same time Sigurd Slembe, another man from Iceland, arrived claiming to be a son of Magnus Barefoot. He claimed to have gone through an ordeal by fire in Denmark to prove his claim. Harald did not recognize him as his half-brother. In 1136 Sigurd murdered Harald in his sleep in Bergen, and had himself proclaimed king. Harald's supporters would not accept him and had Harald's two infant sons, Sigurd Munn and Inge Crouchback, named king. Sigurd Slembe liberated Magnus the Blind from his enforced monastic life and allied himself with him. The war between Sigurd Slembe and Magnus the Blind on the one side, and Harald Gille's old supporters with his young sons on the other, dragged on until 1139, when Magnus and Sigurd were defeated in Battle of Holmengrå fought near Hvaler. Magnus was killed in the battle, Sigurd was captured and tortured to death. 
Question: How many years did the war between Harald's old supporters and Sigurd last? 
Answer type: Number 
Output (English): 3.