When Ephraim spoke, there was trembling. He exalted himself in Israel, But when he became guilty in Baal, he died.
How the mighty had fallen!  There had been many times in Israel's history that saw Ephraim in the ascendancy.  Beginning with the preferred blessing of the Patriarch Jacob  (Genesis 48:14), Ephraim had always been prominent and powerful among the twelve tribes, being the largest and strongest, and at the same time, the most ambitious among them.  They led the rebellion against the house of David (1 Kings 12:20); Joshua, the successor to Moses and leader of the conquest of Canaan was an Ephraimite;[1] after the death of Solomon, the Hebrew dominion in the Middle East attained its greatest extent under the Ephraimite Jereboam II (2 Kings 14:25-27); and here the prophet summarized that long-standing preeminence of Ephraim with the comment that, "When Ephraim spake, there was trembling."  We agree with Myers that there is "no specific reference"[2] here to any particular event that indicated the former power and glory of Ephraim.  The thrust of the verse is in the second clause.