Thanks Palavra,Good morning, Altan, I hope all is well there.
Παρακάτσεψαν is the past tense (3rd person plural) of the verb παρακατσεύω, which means stalk, stake out. Here, however, I would translate it as "peek" (Türçesi dikizlemek olabilir), i.e. The Turks cracked the gate open and peeked through it, only to see [...]