Conshaft or intelligence in an army is so necessary, that without it no direction can be given with assurance, without it we cannot discern betwixt our friends and our enemies, who are with us, or against us, which is the first point a commander hath to know; coming in an enemies' country: Next he ought to know the strength of his enemy's army, foot and horse, that he may the better dispose of his own: he ought also to know how his enemy is quartered in garrison, leaguer, field or dorp, and what watch they keep in all those parts: And how far their horsemen do lie from their foot, and how guarded. To have certainty of all this he must have some secret friend with the enemy, for giving him secret intelligence, and that he should not trust too much in one, he must have a subtle boor, now and then frequenting without suspicion amongst them, as ordinarily his Majesty of worthy memory had: likewise it were needful that they debauched some secretary on their side, for getting the lists of their strengths, officers and soldiers, as also for their qualities, that he might the better dispose himself against them, in directing private parties on the ways they travail to get prisoners, and failing thereof to fall on their watch or within their quarters.
He ought also on all marches to have a known boor with him, to acquaint him with all passes or straits, on which the enemy can repair to him, or from him, conferring his land map with the boor's intelligence, which betime would enable him in knowing all the passes.
Likewise he ought to have intelligence out of the enemies' leaguer, how they were provided of victuals, ammunition or forage, and of their healths, if there were any infections amongst them, or what sport or recreation they used without their quarters, and what streets they go on, and how they are conveyed, striving still to get prisoners, for the better intelligence how their ammunition is kept, and with what guards, that if it were possible, accidental fire might be set to it, and for getting this good of intelligence, the chief officers would be liberal to those whom they put in trust, seeing without it little good service can be effected, and the getting of it is the safety of many cavaliers and their credits.
Therefore whether he be defender or pursuer, intelligence gives him a kind of assurance in all his actions, and the loss, or neglect of it hath robbed many a brave commander of their fame and credit, being surprised through oversight, as Gustavus Horne was at Bamberg: It was also the loss of Hanau, and Philippsburg; Intelligence then being of such moment, it should make generals, and all commanders under them, according to their qualities and charge, to be open handed; otherwise it is impossible to subsist long not being surprised.