How did the Fatimids take advantage of disorder in Egypt in 969?

In 969, the Fatimid dynasty successfully exploited a power vacuum in Egypt following the death of the Ikhshīdid ruler Abū al-Misk Kāfūr in 968.12

Kāfūr had previously maintained stability and thwarted earlier Fatimid attempts to seize the region. However, upon his death, the Ikhshīdid administration collapsed, leaving the state unable to maintain order within its army and bureaucracy. The Fatimid caliph al-Muʿizz, who had previously postponed an invasion out of respect for the treatment his mother received while passing through Egypt, seized this opportunity to launch a decisive military campaign.12

The Fatimid general Jawhar led a Berber army into the Nile valley, successfully occupying the country. Following this victory, the Fatimids established a new capital at Cairo, which served as the base for their continued expansion into Palestine and Syria.312