This agreement , however , was not adhered to , and clashes grew between the Jordanian army and Palestinian militants . In February 1970 fighting broke out in Amman resulting in approximately 300 deaths . Between February and June 1970 , about a thousand lives were lost in Jordan due to the conflict . In September 1970 ; following failed assassination attempts of the king , and the Dawson 's Field hijackings in which 4 planes were hijacked and landed at a desert airstrip in Jordan ; the Jordanian king ordered the army to attack and expel Palestinian militants , and declared martial law . Syria attempted to aid the Palestinian cause in Jordan by sending significant military forces across the border , though nominally under the Palestine Liberation Army command , which were repulsed after some initial successes as a result of Jordanian air force strikes . After a protracted campaign , lasting 10 months , and claiming more than 3,400 Palestinian deaths the king reasserted Jordanian sovereignty . Yasser Arafat and remaining fighters fled to Southern Lebanon
Dawson 's Field hijackings
Dawson's Field hijackings
Jordan Valley