Armed merchants and reaction forces in a space convoy

An East India trade analogy gives merchant ships enough weapons to resist fighters or other light attackers. Heavier escorts would confront an enemy that could afford proper warships. Against a stronger fleet, the escorts could fight a delaying action while the merchants escaped and called for help. Trade routes important enough to support regular convoys could also justify a nearby group of larger warships as a reaction force. These are proposed arrangements within a fictional setting whose travel and combat rules would have to permit them.