1 Kings 15:27

And Baasha the son of Ahijah, of the house of Issachar
A man of that tribe; but who he was, or his father, is nowhere else said, very probably an officer in Nadab's army:

conspired against him;
laid a scheme to take away his life, and seize the kingdom:

and Baasha smote him at Gibbethon;
a city in the tribe of Dan, ( Joshua 19:44 )

which belongeth to the Philistines;
it was a city given to the Levites, ( Joshua 21:23 ) and they being driven from it by Jeroboam, the Philistines seized on it, or had heretofore made a conquest of it; and Nadab was desirous of getting it out of their hands, and therefore besieged it, as follows:

for Nadab and all Israel laid siege to Gibbethon;
and while he was besieging it, Baasha took the opportunity to slay him, where his carcass lay exposed to dogs, or fowls of the air, and had no burial, as Ahijah predicted, ( 1 Kings 14:11 1 Kings 14:13 ) .