How should a party of PCs get past an army to fight the leader?

[The Human Diversion]

Usual disclaimer: Don't read if you're in my Wednesday Night Forgotten Realms Game!

plot!:

So the PCs have followed a few different trails of breadcrumbs to learn that a massive shortage of supplies (especially food) is due to a huge orcish army from the north (The Spine of the World) moving south toward Waterdeep, pillaging everything along the way. Eventually I'd like to have the PCs fight the leader(s) of this army, but I'm not sure how much troop combat I want (if any) or just how the PCs could break through the rear lines to find said leader(s).

Right now the PCs are level 5, and about to level, so teleporting back there is a bit beyond them. Ideally I'd like to at least give them the illusion of choice on how to get there, from my point of view their options are as follows:

1) travel there via mundane means
2) sneak there through the army
3) find a way to teleport there
4) fly there somehow
5) somehow get their target(s) to come to them.

This encounter is important as the main leader is a mythic character and is the PC's entry point to their first mythic level.

So ... if you were a party of PCs, could you think of any other options to "break" my plans?

[Secane]

The party should marry into the Orc army's leadership and have their descendants rule over a world conquered by this Orc army?

Ok, jokes aside, why not try a classic Lone Wolf tactic. The Orc army is moving towards Waterdeep right? So all the party has to do is to hide away in a forest, or the basement of a building (preferably one that is in ruins or otherwise not worth pillaging) and have the party wait for the bulk of the army to MOVE pass them.

Now assuming the leaders of the army is in the center of the army, then just like the "eye" of a hurricane, once the bulk of the army has gone pass them, the party can pop out of their hiding place and head straight for the leaders.

To put it simply the Party don't have to get to the leaders of the army, they can simply hide and let the leaders of the army come to the party.
As long as the party can find a good place to hide away along the path of the army they can easily pull this off.

Now what happens AFTER they kill the leaders is another thing. HOPEFULLY, the army breaks apart with no more leadership. Otherwise the party would need to hide again or run REALLY fast out of there.

[LazarX]

Armies aren't a solid wall of people. They are a collection of groups, usually ragtag that can generally be bypassed with a bit of stealth by a small group.

Distractions can also be a big help.

[Molten Dragon]

Invisibility not an option? . Disguise self either spell or mundane means and sneak through the camp keeping a low profile. Just a couple of things off the top of my head

[boring7]

-How much intrigue do the PCs go for? Barbarian kings ALWAYS have scheming lieutenant ready to get a promotion-by-regicide.

-How much time do they have? Any plan has a hard time limit of "how long it takes the army to get here".

-In Faerun, in Waterdeep? I think they CAN get access to teleport if they pester the right nobles and get some funds out of 'em.

-Check the party's moral compass, is tainting a water supply and infecting the army with a plague an option?

-Inside of every problem is a solution involving high explosivesfast zombie birds strapped to kegs of gunpowder.

[Mathius]

Hippogiffs are 5k per level but could be disounted/gifted by friendly allies.

Scroll of animal shapes is 3k and a druid should be able to eventually make the caster level check.

Hat of Disguise is 1800 per PC to look like and orc and some may not need it.

Try to hire on a mercs.

Get captured and escape to find leaders.

Be a spy.

Scroll of air walk

Overland flight on the PC capable of carrying the rest of the party. (Ant haul and heavy load belt.

If the druid is strong enough, wild shape and carry.

blend spell all around. Kind of hard for the non caster.

[Duiker]

My Reign of Winter group rode an awakened mattress with skis affixed to the bottom that they dubbed the Bed Sled (complete with a pair of Tyrannasaurus skulls mounted the frame, and a dozen children they rescued gradually along the way) straight through the siege on Triaxis, fighting as they went.

I really don't think it can be explained in less than a novella. But it was perfection incarnate. Your mileage, of course, may vary.

[Mike Franke]

As some have said:
invisibility
disguise

how about get hired as mercenaries, this takes disguise up a notch as you do actually belong there once hired.

Journey through much danger to the hidden oracle who will predict the exact location of the general's tent when the army camps on such and such a day. Get there ahead of time and dig a hole to hide in until the general sets up his tent at which point the players spring forth ...

[Mathius]

Let them think of the way in but feel free to restrict funds/availability if you do no want them to just skip to the leader.

A single scroll of teleport is not that expensive and can get them all there if they know where there is. Flight with magic is somewhat more but is really hard to stop when combined with invis.

I would encourage the social or sneaky ways in.