Clues

  1. The man was a soldier. 
  2. A bird sound was the signal to mount an attack. 
  3. The man was shot. 

Solution

The man was a guerrilla, who fought against a foreign army which invaded his country. Together with other soldiers, he planned an attack against an enemy division, moving through the forest under cover of night. A triple "hoot" [fake cry of a tawny owl] was the signal to launch an onslaught. Unfortunately, there happened to be a real tawny owl around which "ordered" guerrillas to set off at the wrong time, heading straight into enemy rifles. The man, as well as a few soldiers with him, lost their lives; the others managed to escape.