Work of an Invader, the 9th book of Arthashastra includes the subjects, such as, the knowledge of power, place, time, strength and weakness; the time of invasion; the time for recruiting the army; the form of equipment; the work of arraying a rival force; considerations of annoyance in the rear; remedies against internal and external troubles; consideration about loss of men; wealth and profit; internal and external dangers; persons associated with traitors and enemies; doubts about wealth and harm and success to be obtained by the employment of alternative strategic means.

According to the Work of an Invader a conqueror should have comparative power and strength to challenge the opposite king with either more strength or of equal power. Having ascertained power, place, time, time of marching, recruitment of army, their potentiality to fight a war, the consequences of the war its level of gains and its consecutive losses the King can then march towards the enemy army with full strength. Without proper knowledge the King may have to face adverse consequences for which he might not be prepared.

Work of an Invader separately discusses the elements which are considered within power, place, time and space. Kings who possess power is better of than one possessing skill as in time of crisis it will be power which will help the king to win the war. Again the second requirement of an invader is to search out the space for waging the war. Time mainly consists choosing between of cold, rainy and hot weather. The selection between day and night and between seasons, solstices, years and Yuga remain at discretion of the king. According to Kautilya the invader who possess strength, time and place is accomplished enough to march against his enemy.

Work of an invader after this is to recruit his army and reorganise him self with proper equipments and proper information regarding the enemy resource and their war strategies. The troops can be hereditary troops; hired troops, cooperation of troops as well as troops belong to a friend and wild tribes .All form an army of a kingdom as a whole. The King is bestowed with the responsibility to assess the requirement of the war. It is he who will understand whether hereditary army is sufficient or not and as such will give instructions to the hired ones (if any) and the other types of soldiers. Each type will have separate levels of instructions.

Work of an Invader in the following chapter includes the assessment of the attitude of the rear kings and the classification and remedy of internal as well as external troubles. This chapter mainly indicates towards the intrigues which appear in the invader's army as they can be provoked about the profit made in the front which includes the ruler himself. Book XI also assesses the loss of trained men and money. Further it takes into consideration the assessment of internal and external dangers and verification of persons who are associated with traitors and enemies.

Thus, Work of an Invader describes all the requirement of an invader as he proceeds towards waging a war against an enemy country, the resources he is supposed to check and the followed up measures he is supposed to take along with the upcoming battle.