Duties of a Messenger, as described in chapter I of Book XII in Arthashastra, mentions about such situations when a weak king is attacked by a powerful enemy. Kautilya advises such a king that he who surrenders like a crab before the enemy lives a life of despair; hence in such conditions when the enemy is stronger then the weak king should seek the protection from an equally powerful king or should maintain himself in an impregnable fort. While he defines invaders of three types - a just conqueror, a demon likes conqueror and a greedy conqueror. A just conqueror is satisfied with mere obeisance and so it shall be favourable for the weak king to take his protection; a demon like conqueror on the hand his, does not remain contented with seizure of land, treasure, sons and wives of the conqueror but also takes away the life of the latte i.e., the conqueror. Hence the weak king should keep such an invader away from himself at any cost. A greedy conqueror on the other hand usually remains satisfied with what he gains easily in the form of land as well as money and does not intend to take away lives. A weak king can take rescue of such invader as they can be satisfied with gifts and conciliations as well as shredding off some territory or piece of land to the invader.
Duties of a Messenger further mentions that when any one of these arises to go against and attack the weak king, the latter should avert the invasion by making a treaty of peace or by taking recourse to battle of intrigues or by treacherous fight in the battlefields. He may seduce the enemy`s men either by conciliation or by giving gifts and should prevent treacherous proceedings within his own men by either sowing seeds of dissensions among them or by punishing them. Spies under concealment may capture the fort of the enemy, country, or camp with the aid of weapons, poisons or camp; he may harass the enemy`s rear from all sides and may devastate the enemy`s country with the help of wild tribes. The weak king can use all such methods where he can set up a scion of enemy`s family and can even imprison the prince to seize the enemy`s territories. When all the methods of mischief have been perpetrated then the weak king can send his messenger to the enemy to sue for peace or he may make friendship with the enemy without offending the latter. If the enemy still continues to march then the weak king may also offer him with one fourth of his wealth and land to the invader in order to make peace with him which shall take place in the lapse of day and night.
Duties of a Messenger mentions that if the invader is persuaded in making peace with the weak king on return of surrendering of the weak king and his army; he may give the weak king on return the elephants and the cavalry which are uncontrollable; or he may send some of his army which is full of traitors, enemies and wild tribes under the control of trusted officers. The enemy may send his own trusted hereditary army which shall be able to hurt the weak enemy at the time of trouble. Overall the invader shall return only steps of intrigues to the weak king who has surrendered to the invader in order to avoid war.
Thus, Duties of a Messenger suggests some methods to the weak king to avoid war within unequal powers and halt to peace as long as possible. Arthashastra suggests that the weak king should make all efforts to take care of his own people who are the real strength of the weak ruler in case of a clash between him and the invader.