Charles Ellicott Commentary 2 Kings 14:19

"And they made a conspiracy against him in Jerusalem; and he fled to Lachish: but they sent after him to Lachish, and slew him there." — 2 Kings 14:19 (ASV)

Now ... but. — And ... and.

They made a conspiracy. — The fact that no individual conspirators are mentioned appears to indicate that Amaziah’s death was the result of a general disaffection; and this inference is strengthened by the other details of the record. Thenius supposes that he had incensed the army in particular by some special act. Probably his foolish and ill-fated enterprise against Israel had something to do with it.

Lachish. — Now Um Lâkis. Formerly it was a strong fortress. (Compare 2 Chronicles 11:9; 2 Kings 18:14; 2 Kings 19:8.) Amaziah’s flight there seems to indicate either a popular rising in Jerusalem or a military revolt.

They sent after him to Lachish. — This, too, may point to a military outbreak.