Machiavelli on Mercenaries
Mercenaries and auxiliaries are both useless and dangerous.
Anyone who relies on mercenary troops to keep himself in power will never be safe or secure, for they are fractious, ambitious, ill-disciplined, treacherous.
They show off to your allies and run away from your enemies.
They do not fear God and do not keep faith with mankind.
A mercenary army puts off defeat for only so long as it postpones going into battle.
In peacetime they pillage you, in wartime they let the enemy do it.
This is why: They have no motive or principle for joining up beyond the desire to collect their pay.
And what you pay them is not enough to make them want to die for you.
They are delighted to be your soldiers when you are not at war; when you are at war, they walk away when they do not run.
It is true that occasionally a ruler seems to benefit from their use, and they boast of their own prowess, but as soon as they face foreign troops their true worth becomes apparent.
Experience shows individual sovereigns and republics that arm the masses are capable of making vast conquests.
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This will upset Sikh Empire fanboys, but it's an indisputable part of why things went pear-shaped.