Jordan and Palestine have never had any sort of conflict at all, ever.
What is Black September?
{...
Black September (Arabic: أيلول الأسود; Aylūl Al-Aswad
), also known as the Jordanian Civil War was a conflict fought in the Hashemite Kingdom of Jordan between the Jordanian Armed Forces (JAF), under the leadership of King Hussein, and the Palestine Liberation Organisation (PLO), under the leadership of Yasser Arafat, primarily between 16 and 27 September 1970
...
After Jordan lost
control of the
West Bank to
Israel in
1967,
Palestinian fighters known as
fedayeen moved their bases to Jordan and stepped up their attacks on Israel and
Israeli-occupied territories. One
Israeli retaliation on a PLO camp based in
Karameh, a Jordanian town along the border with the West Bank, developed into a full-scale battle. The perceived joint Jordanian-Palestinian victory against Israel during the 1968
Battle of Karameh led to an upsurge in
Arab support for the fedayeen in Jordan, in both new recruits and financial aid. The PLO's strength in Jordan grew, and by the beginning of 1970, groups within the PLO had begun to openly call for the overthrow of the
Hashemite monarchy.
Acting as a
state within a state, the fedayeen disregarded local laws and regulations, and even attempted to assassinate King Hussein twice—leading to violent confrontations between them and the
Jordanian Army in June 1970. Hussein wanted to oust them from the country, but hesitated to strike because he did not want his enemies to use it against him by equating Palestinian fighters with civilians. PLO actions in Jordan culminated in the
Dawson's Field hijackings incident of 6 September, in which the
PFLP hijacked three civilian aircraft and forced their landing in
Zarqa, taking foreign nationals as hostages, and later blowing up the planes in front of international press. Hussein saw this as the last straw, and ordered the army to take action.
[10]
On 17 September, the Jordanian Army surrounded cities with significant PLO presence including
Amman and
Irbid, and began shelling Palestinian refugee camps where the fedayeen were established. The next day, forces from the
Syrian Army, with
Palestine Liberation Army markings, intervened in support of the fedayeen and advanced towards Irbid which the fedayeen had occupied and declared to be a "liberated" city. On 22 September, the Syrians withdrew from Irbid after the Jordanians launched an air-ground offensive that inflicted heavy losses on the Syrians. Mounting pressure by Arab countries (such as
Iraq) led Hussein to halt the fighting. On 13 October he signed an agreement with Arafat to regulate the fedayeen's presence in Jordan. However, the Jordanian military attacked again in January 1971 and the fedayeen were driven out of the cities, one by one, until 2,000 fedayeen surrendered after
being surrounded in a forest near
Ajloun on 17 July, marking the end of the conflict.
[11]
Jordan allowed the fedayeen to leave for
Lebanon via
Syria, and the fedayeen later participated in the 1975
Lebanese Civil War. The
Black September Organization was founded after the conflict to carry out reprisals against Jordanian authorities, and the organization's first noted attack was the assassination of Jordanian Prime Minister
Wasfi Tal in 1971 who had commanded parts of the operations that expelled the fedayeen. The organization then shifted to attacking Israeli targets, including the highly publicized
Munich massacre of Israeli athletes. Even though Black September did not reflect a Jordanian-Palestinian divide, as there were Palestinians and Jordanians on both sides of the conflict, it paved the way for such a divide subsequently.
[12
...}
The PLO is one particular organization, and is not very Palestinian, as Yasser Arafat was Egyptian.
But apparently the fedayeen was rebel Jordanians and not Palestinians.