I. Avoid war by every possible means, in all possible circumstances, but always act as if war might start at any time. Train intensively and be ready for battle at all times -- but do not be eager to fight. The highest purpose of combat readiness is to reduce the probability of having to fight.
II. Gather intelligence on the enemy and his mentality, and monitor his actions continuously. Efforts to do so by all possible means might not be very productive, but they are seldom wasted.
III. Campaign vigorously, both offensively and defensively, but avoid battles, especially large-scale battles, except in very favorable circumstances. Don't think like the Romans, who viewed persuasion as just an adjunct to force. Instead, employ force in the smallest possible doses to help persuade the persuadable and harm those not yet amenable to persuasion.
IV. Replace the battle of attrition and occupation of countries with maneuver warfare -- lightning strikes and offensive raids to disrupt enemies, followed by rapid withdrawals. The object is not to destroy your enemies, because they can become tomorrow's allies. A multiplicity of enemies can be less of a threat than just one, so long as they can be persuaded to attack one another.
V. Strive to end wars successfully by recruiting allies to change the balance of power. Diplomacy is even more important during war than peace. Reject, as the Byzantines did, the foolish aphorism that when the guns speak, diplomats fall silent. The most useful allies are those nearest to the enemy, for they know how best to fight his forces.
VI. Subversion is the cheapest path to victory. So cheap, in fact, as compared with the costs and risks of battle, that it must always be attempted, even with the most seemingly irreconcilable enemies. Remember: Even religious fanatics can be bribed, as the Byzantines were some of the first to discover, because zealots can be quite creative in inventing religious justifications for betraying their own cause ("since the ultimate victory of Islam is inevitable anyway …").
VII. When diplomacy and subversion are not enough and fighting is unavoidable, use methods and tactics that exploit enemy weaknesses, avoid consuming combat forces, and patiently whittle down the enemy's strength. This might require much time. But there is no urgency because as soon as one enemy is no more, another will surely take his place. All is constantly changing as rulers and nations rise and fall. Only the empire is eternal -- if, that is, it does not exhaust itself.