I will break the staff of bread - They shall be besieged till all the bread is consumed, till the famine becomes absolute; see 2 Kings 25:3; : "And on the ninth of the fourth month, the famine prevailed in the city; and There Was No Bread for the people of the land." All this was accurately foretold, and as accurately fulfilled.
Abp. Newcome on 2 Kings 25:6; observes: "This number of years will take us back, with sufficient exactness, from the year in which Jerusalem was sacked by Nebuchadnezzar to the first year of Jeroboam's reign, when national idolatry began in Israel. The period of days seems to predict the duration of the siege by the Babylonians, 2 Kings 25:9, deducting from the year five months and twenty-nine days, mentioned 2 Kings 25:1-4, the time during which the Chaldeans were on their expedition against the Egyptians; see Jeremiah 37:6." This amounts nearly to the same as that mentioned above.
The staff of bread - Bread is so called because it is that on which the support of life mainly depends.
With astonishment - With dismay and anxiety at the calamities which are befalling them.