"Well, one of the most important things in any battle is information.  If you have information you can make decisions that will benefit your cause while be harmful to your enemy.

=="Good. Start with the fundamental principles and work your way out to the specifics." He looks encouraging, and you realize he's quite serious about his plans for you.

If I were to be planning an attack on the city, I would have sent in about a score of people over the course of a few months to integrate into the city and find out information on what the city is capable of.

=="A good point, but in fact, three months ago, the city was in the hands of a duke loyal to the king who commands the general of the besieging force. The current master of the city, Raj Whitehall, has invaded into Brigade lands and taken one of their great cities which guards the trade pass over the hills to the coast. Three months ago, he was on the other side of the ocean trying to get good biscuits loaded onto his ships while scheming bueraucrats were trying to substitute biscuits laden with maggots, and pocket the difference. As you say, information."

  As well as guard rotations, when the city is mostly busy, etc.

=="Quite right. Its a city before arc lighting or gas lighting, so nighttime activities are by torch and lantern."

  The key to having a score of people over a few months, is to make sure none of them know each other so that should one get caught, it will not endanger the others too much.

=="A cell structure of sleepers. Nicely crafted."

  Also, having it be over a few months makes it less suspicious than just a score entering at the same time... unless of course there was a festival going on, in which case it would be an opportunity to move people in.

=="In fact, there was a festival. The High Summer worship. The locals worship the Spirit of Man of this Earth. The invaders worship the Spirit of Man of the Stars. The chief difference is that the invaders say humans are not native to this planet."

Once information has been gathered, I would proceed to train my men in ways to counter what the opposing army has.

=="Thousand pound dog cavalry, some smoothbore cannon with..."  He holds out a hand and a bowling ball sized cannonball appears. "10 mm muskets. The invaders have also 12 mm rifles. Shades of Davy Crockett, for you. The defenders also have axes and pikes. Swords are plentiful, typically sabres for the cavalry and longswords for the footmen."

  For instance, the man in the city has riflemen on the walls and men on horses.

=="Dogs. And they like to fight. A fighting dog has its teeth sharpened by a file. Imagine fighting a thousand pound wolf with a single shot pistol armed rider with a cavalry sabre. It is not fun for the pikemen if their line breaks."

  I would actually work on training men with bows, to fire from a distance.  If the attack is at night, it would be hard to see the amount of arrows being fired and where they are coming from.

=="Going lo-tech. Very interesting."

  So attacking from the sides and up front to begin the battle would cause confusion and divert the city's force of troops from a specific area, since they would not know where to defend from.

=="Yes, I think that could work."

  Bow and arrows can be especially effective because while not necessarily lethal to the effect of guns, they can cripple people and horses, removing them from the battle.

=="Wounded dogs have a tendency to frenzy. Better training stops this, but only partly."

 If you had people with spears up front to be sacrificed but preventing the cavalry to charge, you could have archers shoot from behind relatively safe lines and take down that force.  Catapults are an effective means to take down walls, and buy time for yourself while distracting the enemy, or cannons depending on how developed the world is.

=="Cannons. Simple ones, but iron."

  But in this case, I'll stick with catapults.  If positioned away from the army and attacking from elsewhere, the person in charge would have to divert troops otherwise his city would be destroyed.

Once troops are diverted there are a few things that could occur, it would depend on who went to take care of the distraction.  If it was the relatively quick cavalry, then the spear men could open up and let the ground troops through, if it was someone else, archers could take care of them.

On the other hand, if ranged support such as artillery and archers and riflemen and such can be kept safe for a time, then they can fire at will to take care of the opposing army's force and wear them out while the ground troops get rest.  Once they are rested and ready, and the enemy is tired, they can fight a weakened enemy.

However this is all hypothetical, and most decisions have to be made in reaction to what is going on.

For instance, if the cavalry were defeated earlier and then the distraction started, then the main force would be diverted, thus the opposing army would be able to pull ahead.

If I were defending the city, then I wouldn't do much different, although I would see about causing chaos within the enemy ranks.  If things get bad I would do a slow and steady retreat within the city and take down the opponent at range. Then go from there."

Thinking for a moment...

"On the other hand, if those tactics were used against me and I was defending the city, then I would surrender.  Dead men don't get revenge.  After giving them a false sense of superiority, take out their leaders, and without someone to lead them, chances are the ground troops will become disorganized.  It is at that time, you pose a question to the army.  Do they want to surrender and live? Or do they want to die? Without a leader, their chances of succeeding, even if they have more men are slimmer since it is hard to co-ordinate that many troops, unless they have extensively trained with their leaders and with each other.  Also, a chain of command has to be established, so that should leaders die, there are those that can take their place and lead the men.

=="You are one scary guy. Nasty." He smiles like a shark.

A sign of sorts should be used to recognize someone as a leader, and have several men having it, with perhaps something special for the general in charge of the army.  Then have several trained leaders with hidden symbols to use to organize the men should all the visible leaders be killed.

Again, there are many possible outcomes and strategies to use in a war, but this is what comes to mind off the top of my head."