The men of Israel were distressed that day; for Saul had adjured the people, saying, Cursed be the man who eats any food until it be evening, and I be avenged on my enemies. So none of the people tasted food.
The direct results of Saul's stupid pagan oath was that his men became fatigued, and from hunger were unable to exploit the opportunity to destroy the Philistines.  The great majority of them escaped  (1 Samuel 14:30).  Also, when the evening finally came, and the curse was lifted, the people were so hungry that they slaughtered animals for meat but did not take time to bleed it perfectly as God's law commanded, consequently bringing the whole army into sin against God. No greater disaster for Israel could be imagined.  Then, in addition to all that, Saul found himself compelled to condemn Jonathan to death.