The Israeli army had expected to find Yahya Sinwar somewhere in the network of tunnels he had helped to expand and perfect since his return to Gaza, in 2011. Instead, he was killed in broad daylight, after more than a year of deadly war, during an Israeli army patrol in the south of the enclave.

He was born in 1962, in the Khan Yunis refugee camp in the enclave's south, where his parents, originally from Ashkelon, fled to during the Nakba, the forced exodus of some 700,000 Palestinians after the state of Israel was created in 1948. In those troubled times, the neglected town of Khan Yunis became a stronghold of support for the Muslim Brotherhood, an Islamist movement that was started in Egypt to resist the British occupation.

His political consciousness grew, especially after he began studying at the Islamic University of Gaza, founded by the Muslim Brotherhood, where his activism led to his first arrest by the Israeli authorities, at the age of 19, in 1982, when the enclave had been occupied by Israel since 1967. He was arrested again in 1985, which earned him the trust of a man named Ahmed Yassin, who would go on to found Hamas in 1987.

Sinwar, along with a small group of radical militants, who were more fighters than apparatchiks, formed the Palestinian Islamist movement's first intelligence and security unit, which was named al-Majd ("the glory"). The group was dedicated to hunting down Palestinians who collaborated with Israel, and more broadly to fighting anyone who deviated too openly from the organization's Islamist ideology.

His goal was to internally strengthen the organization, even if it meant interrogating, torturing and killing his victims himself, as he had boasted to the Israelis – this earnt him the nickname "The Butcher of Khan Yunis," after his home town. He was once again arrested by the Israelis in 1988, and sentenced to four life sentences for murdering 12 Palestinians considered by Hamas to have been collaborators with Israel.

He was incarcerated for 22 years. During his time in prison, he established himself as a leader among the other Palestinian prisoners. He also learned Hebrew. Israeli army reserve colonel Doron Hadar, who met him on several occasions, described him to Le Monde, in August, as a "realist." "He knows Israelis very well. He read our newspapers, watched our TV shows. He's also a narcissist with maximalist goals, who needs to be in control all the time," Hadar added.

Sinwar was released in 2011, as part of a deal to exchange 1,027 Palestinian prisoners for Israeli soldier Gilad Shalit, who had been held captive by Hamas for five years. He left one prison, only to become trapped in another: He was released in Gaza, but the enclave had since come under an Israeli-Egyptian blockade, instated after Hamas took exclusive control of it in 2007, following a brief intra-Palestinian civil war.

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