NET

21 But a suitable day came, when Herod gave a banquet on his birthday for his court officials, military commanders, and leaders of Galilee.

Darby

21 And a holiday^D7009 being come, when Herod, on his birthday, made a supper to his grandees, and to the chiliarchs^D7010, and the chief [men] of Galilee;

Darby Bible Notes

holiday - The meaning is doubtful. perhaps 'convenient day,' i.e. to Herodias's future purpose. Not a festival, but a leisure day. chiliarchs - Commanders of 1,000 men.

KJV

21 And when a convenient day was come, that Herod on his birthday made a supper to his lords, high captains, and chief [estates] of Galilee;