The PLF was originally founded by Ahmed Jibril in 1959. In 1967 it merged with two other groups, Heroes of the Return and The Youth of Revenge Group. The organization that resulted was the Popular Front for the Liberation of Palestine (PFLP) which was led by George Habash. Jibril spilt from this group in April 1968 to form the Popular Front for the Liberation of Palestine - General Command (PFLP-GC).
The PLF was re-established on April 24, 1977, due to a split in the PFLP-GC. The split was due to a confrontation between Syria and PLO in Lebanon and Jibril's support of Syria. The new organization was headed by Muhammad Zaidan (Abu Abbas) and Tal'at Ya'akub.
In 1982, following the Lebanese War, the organization split into three factions. All three claimed to represent the mother organization and kept the same name:
The faction led by Abbas led many prominent attacks and due to its actions the PLF was designated a foreign terrorist organization. One notorious incident was the attack on the Italian cruise ship Achille Lauro on October 7, 1985. The attackers' original aim was to use the ship to slip into Israel. However, crew members discovered them cleaning weapons and they hijacked the ship. What followed was the murder of an elderly wheelchair-dependent Jewish New Yorker, Leon Klinghoffer. US fighter planes forced down the Egyptian aircraft in which Abbas was travelling following the hijack. The Italians let him go, but subsequently sentenced him to five life sentences in absentia. Abbas was expelled from Tunisia and established his headquarters in Baghdad, Iraq.
In May 1990, the PLF lauched an attack on Israel's Nizanim beach. They intended to kill tourists and Israeli civilians but the operation was aborted. The failure of Yasser Arafat to condemn this attack led to the US breaking up peace talks that had begun in 1988.
Until recently the leaders of the PLF were politically active in the PLO with Abbas being elected to the executive committee. During the years after the PLO signed the 1993 Oslo Accords, Abbas agreed to abandon terrorism and acknowledged Israel's right to exist.
During the 2003 US-led War on Iraq Abbas was captured in April, 2003, by US forces and will presumably be deported to Italy. American warrants for his arrest were dropped when he was convicted in Italy.