Thanks to the SDA crew, and to Cortez because he pointed out 1 improvement thing in the first level :) I kept the run secret mostly, not entirely sure why but somehow I felt like doing that.
In case you're wondering why I did the run on Easy instead of Hard, the reason is simply because most of the levels already take a long time and on Hard the time would at least double. Not to mention that the unit retardation would be more annoying on Hard ;)
You'll also see in the beginning levels that I destroy my units at the end, because initially I thought that I would receive XP by doing this, but apparently that's not the case. Because when you kill them you can see these funky numbers floating around, but they're just Population numbers which are usually represented as yellow and red numbers, though I've seen green numbers too but I actually think that's a little graphical screw up, I think...
I've also noticed a bug in this game (Or at least I think it's a bug, and otherwise it's a very strange feature...) where, if you go to your Home City from within your level select menu, you'll lose 2 XP everytime you visit there this way. This strange thing has caused a bit of discontinuity (To my disadvantage mind you) between level 4 and 5 (You can't see this in the run but it's a difference of 2 XP), and level 9 and 10 (I needed to enter the Home City everytime before starting level 10 which is how I found out about this strange thing since the total XP amount kept decreasing). I didn't backup the Home City information when I was working on the runs since I thought it was included in your profile, but it wasn't, so I couldn't restore it. It's in my disadvantage and the difference is minor anyway, so...

Well, I think that's about it, enjoy the run!

Level 1 - War Dance (2:26)

Heh, the first Primary Objective is getting Nathaniel Black to the War Chief, but taking his uncle (Kanyenke) to the War Chief works just as well. Though I think that the War Chief is a little confused when I arrive there with Kanyenke ;)
The actual main objective in this level is destroying one of the two enemy Town Centers. And I pick the left one because there's more resistance at the Town Center on the right.
As soon as I get controle over the little village, I manually destroy the War Hut as fast as possible in order to trigger reinforcements (They arrive at the bottom of the map).
It's just a matter of quickly getting a shitload of units to the enemy Town Center. Also, the moment I start attacking the Town Center, the enemy reinforcements show up but I don't bother with them.
Thanks to Cortez for pointing out to me that I shouldn't bother killing the enemy War Chief, which I did in previous attempts ;)

Level 2 - The Rescue (2:54)

This level is just rushing and crushing to the objective. A very important thing in this level is to keep the Falconet intact, because it needs to destroy the prison from a distance while my army distracts all the enemy units at the cave entrance. A nice thing at 2:41 (In-game timer) is that my shielded unit just barely was there in time to block the enemy unit that was heading towards my Falconet :)
An annoying thing in this level is that my units sometimes randomly started to attack the enemy in the middle of the level, which must not happen because then they come after me. So I really needed to keep them on the move and trying to avoid the units from having brief pauses (Which can happen if they bump in each other).

Level 3 - Breed's Hill (20:21)

The reason this level is so long, is because it can't be speeded up. The level will always have the set time of 20:21, so it's only a matter of staying awake... ;)
Well, I'm just creating lots of Canoes and War Canoes and put those at the enemy spawn points to intercept their boats, so they can't even reach the shore to drop off some units. There's no way they can ever capture the Redoubt.
All other things I do in the level is just a bit of XP gathering and such, and that's about it.

Level 4 - Crossing the Delaware (5:34)

First thing is freeing the Falconet, since it's quite good at destroying stuff... Then systematically destroying the tents while evading most of the patrol, killing the patrol takes too much time. After having destroyed all the tents, I need to make 2 fires. And here comes the tricky smartassed level glitching part ;)
After you've build 2 fires, you need to go with your army to the Town Center at the top of the map while a big enemy army is moving towards the city you've just put the fires up (It's a distraction). After the second fire has been build, I already have units on top which I then order to quickly kill the enemies there which must be killed in order to take over the town. Now the awesome thing is that since I've killed those enemies very quickly, I've quickly taken over the town, and then the town at the bottom will get in control of the enemy BUT the big enemy army isn't close enough to this area yet and then for whatever reason the big enemy army will turn into a third party and they'll just stop moving. Because of that there will be no enemies (Except some Settlers and the tower) in the town below and I can just happily destroy the Capitol and complete the level.

Level 5 - Saratoga (12:57)

In the beginning I need to take out the 3 Fort Wagons with my little army. The other enemy units need to be killed too otherwise there won't be a little army left... Unless I would wait for the Fort Wagons to show up and come down the road but hey, this is a speedrun, no time to wait :) Destroying the 3 Fort Wagons triggers reinforcements/base deployment, so getting that done as fast as possible is crucial.
When my base arrives, I need to gather A LOT of resources in order to age up and build my own 3 Fort Wagons which in turn will complete the level. In the meantime I use my little army again to quickly take out the brown enemy (Burgoyne's Supply Line) so that they won't show up with enemy units at my base everytime and also to noticably slow down the arrival of enemy Fort Wagons (Hence the Supply Line part). Taking out their base is easy since they didn't have any time yet to build up much.
With a Falconet I also destroy Kuechler's Bridge to complete the Secondary Objective, even though it's secondary, it's very useful because otherwise Kuechler's army will show up and will start attacking my base which isn't very convenient... If the bridge is destroyed, the arrival of his army will be delayed a lot.
I'm doing something tricky with the Fort Wagons which maybe isn't all too obvious (At least I didn't think of it in the beginning of attempting this level, I actually noticed it by accident sometime :) Though it's something that you do a lot with normal units) but it saves a lot of time. I start creating the second Fort Wagon at a certain time (Which is purely guessed since it's rather difficult to determine it exactly because of unit/Settler randomness) so that when the second Fort Wagon is almost finished creating, I can start creating the third Fort Wagon which means that the third Fort Wagon will be added to the second Fort Wagon's queue, which means that the third Fort Wagon will be created in mere seconds (7 seconds in my run to be exact).

Level 6 - Valley Forge (8:12)

First priority is getting enough Wood to build 6 houses. Funny thing is that my units are automatically dying in the beginning of the level until the 6 houses are built, then all of a sudden they can withstand the cold while they're still just outside :D After that I need to gather a lot of Food... So I locate some lost Supply Wagons and get help from the Baker (Only the Baker at the bottom since the other one on the right side of the map is too close to enemy units. Also, you can only send 1 Supply Wagon from the Baker at a time, which makes the Baker on the right side completely useless...).
After the Food is gathered, I grow in unit number, taking out some enemy towers with the Falconets to clear the way to the enemy Fort and then it's just full force on destroying the Fort. My Infantry units on first row so the enemy concentrates their fire on them to preserve my 2 Falconets (Note that in the run one of the 2 Falconets suddenly decided to start attacking another building... Why the hell he did that, I don't know, I guess the Fort wasn't very interesting). A funny thing is that after the Fort was destroyed, I killed all my units but Hero units can't be killed manually, and yet they were killed just before the Victory message showed up, so my entire army was killed :D

Level 7 - The Battle of Morristown (6:33)

Taking out the enemy village (And that means everything) along with freeing the Iroquois Prisoner opens up the path to the rest of the level because otherwise it's blocked off by an invisible wall... Destroying certain buildings in this enemy village grants me Artillery reinforcements from General Washington, so it's a must to destroy those buildings quickly.
When the path is open I try to rush as fast as possible to the enemy army that's supposedly be heading to Morristown. Hehe, you're probably wondering why they haven't moved yet, right? :) It's because I didn't destroy the front gate part at the place where the path opened up. After this army is killed, Kuechler will be spawned and a combined Artillery shot quickly makes toast of him (The guy barely set foot on the land).

Level 8 - The Battle of Yorktown (3:55)

Initially I thought this level would be quite tricky to get done, but it's actually very simple. I mean VERY simple. I take out the 2 enemy towers (Take note of the way I make use of the shooting delay to move my Falconets up towards the river) to spawn the reinforcements/base. I also build a Fire Pit to grant me some extra unit damage. After that it's just moving to the enemy Town Center with my entire army and crushing it like there's no tomorrow. The Redoubt just before the Town Center is heavily guarded and needs to be dealt with. First destroying the Redoubt Cannon is a must since that thing is very powerful, with 1 blast it can take out mutiple units (I mean literally waves of units). Then I kill most of the Infantry there especially those elite guards, those guys are tough units.
A funny thing is when I'm passing the first Redoubt is that Nathaniel Black says it needs to be destroyed before even hoping of getting to Yorktown, while I just ignore it and go to Yorktown anyway. The French allies will also, well, I wanted to say "help" but they're completely useless. Sure they'll help destroying the first Redoubt a bit, but after that they'll just be standing still and won't do anything, until some minutes have passed and they decide to move to the second Redoubt... So in the meantime of French ally lazyness, I already obliterate Yorktown ;)

Level 9 - The Bozeman Trail (9:39)

Building 2 Trading Posts need to be done quickly to get the base deployed, so keeping Chayton Black on the move is a priority. When the first Town Center is put up, I collect some materials already because when the second Town Center is up, I need to age up to get more units. After that it's just taking out the 2 enemy Town Centers as quickly as possible. I put Holme in the front row for the first enemy Town Center so that the enemy will attack him (Chayton Black already had his share of damage...), and Heroes can take quite some impact which means that the rest of my army can attack the Town Center for a longer time. I can't immediately attack the first enemy Town Center though before some unit reinforcements arrive, otherwise I would be butchered. And the more units I lose, the longer it takes to destroy the Town Center. So I start attacking it just before some unit reinforcements arrive.

Level 10 - Red Cloud's War (7:12)

This level is very simple since like 95% of the level has a fixed time because of the Miners (Of course it's important to keep them alive till they reach your town, otherwise you get additional Miners/enemy waves). So the only part that actually really matters timewise is building the 2 Trading Posts. Well, not much more to say about this level. Chayton Black and Holme also pay a very short teatime visit to their friendly neighbors, the Hole in the Wall gang.

Level 11 - Claims (1:54)

This is another very simple level. The only thing to do is taking out the Barracks at the bottom and the 2 War Huts on top. I use the Falconet to destroy the Barracks because it can easily shoot through the gate. The only other thing worth mentioning here is that when I've destroyed the second (And final objective part) War Hut, I kill my units to interrupt the Victory speech which causes an instant completion of the level without the need to wait for the speech to finish.

Level 12 - Ambushed! (5:47)

This level is funny :) The entire level is infested with the enemy, but I'm not bothering much with them. Originally I took Chayton Black to the top immediately (Led by a Settler since he can't do the entire trip alone without dying) so that a Powder Wagon would spawn at my Town Center, and then I would take the secret pass to the right side of the map. But a Powder Wagon is also spawned when destroying the first enemy Town Center you'll encounter. So I get a lot of units quickly and then destroy the Town Center, I take the units (Which serve as cannon fodder), Chayton Black and the Powder Wagon and just walk straight up to Crazy Horse. Near the end I create a new group of Chayton Black and the Powder Wagon and kill the other group because they could get in the way at the end. Chayton Black now also serves as a bit of cannon fodder to protect the Powder Wagon in the last enemy part.
Also, the whole walking route to the top can be pretty random, especially because of animals that are on the road, not to mention enemy units or just overall unit retardation (Especially the point at 3:37 in-game time, because at this point units sometimes go back and start walking on the right side below, which is very annoying).
I also found a little glitchy thingy in this level which unfortunately didn't prove useful with this strategy (It was useful with my initial strategy), the glitch is spawning an infinite amount of Powder Wagons :) When Chayton Black reaches the top Weapon Cache, a Powder Wagon is spawned at the Town Center. Now if you create a group with this Powder Wagon (Or add it to another group) then a new Powder Wagon will be spawned. If you add that one to a group too, a new Powder Wagon will be spawned, etc. Pretty funny to have 100 Powder Wagons and then blow them all up at once, gives a rather nice explosion.

Level 13 - Turning Point (11:16)

This level was annoying, boring and also absolutely not logical. Holme sends some Settlers to a forest nearby to chop Wood which he needs to rebuild his Fort. The forest is closeby but it's entirely exposed to the enemy making it not safe for the Settlers (Hence why I need to protect them...). But there are also trees around the Fort and especially below the Fort where the Settlers would be much more protected :D And, last but absolutely not least, I have 3 Trading Posts under my controle which deliver resources, including Wood. So why can't I just give Wood to Holme so that he would've rebuilded his Fort in no-time? :D
Anyway, so I just use my units to stop the enemy waves and I just keep on building extra units. There's a trick in this level which makes completing the level much faster, but it involves me having a lot of units (Which is also why I let the enemies kill the Settlers and just wait a bit with killing them). When Holme has gathered enough Wood, I put all my units in the right-corner of Holme's Command Post, since destroying it completes the level. Luck is involved here and a good number of units to be able to destroy it, as you can see Holme has quite a massive army, but when I stand in the corner, a lot of them won't attack or very late. After the Command Post is destroyed, my little army gets entirely massacred :D Ah well, job well done.

Level 14 - Trust (8:18)

This level is all about XP gathering, and I think most of the level speaks for itself. The little, but very valuable, tents throughout the level give me quite a lot of XP, so I'm destroying most of them if not all actually. I also upgrade the Trading Route so that it delivers XP quite a bit faster. Killing Outlaws all over the place also gives lots of XP, so I'm killing them all :) In order to capture Holme, you only need to destroy the Gattling Gun... So I use Cavalry since they have faster movement and are good at melee combat.

Level 15 - Battle of the Little Bighorn (10:41)

This level is a piece of cake, and only the last part matters timewise since the beginning part until Custer's Scouts arrive has a fixed timespan. In this fixed timespan it's very important though to destroy the 6 buildings along the scouts path before they arrive, otherwise the scouts will have a very long pause (I'm not sure how much exactly, but it's at least a minute, probably much longer) at each of those buildings until they move on. But if you've destroyed all 6 buildings, the scouts will move on immediately without pausing which saves a lot of time (And units, since there won't be extra enemy units at the end of the level). I also use a Flaconet to destroy one of the buildings. Quick, easy and efficient.
Well, after those 6 buildings are destroyed, I need to wait, for a very long time :D So in the meantime I get some more units, and also some more Settlers to fill my Fire Pit to the max so that the Fire Pit can provide maximum unit damage for the end fight.
When the pass opens up, I destroy Custer's Scouts because otherwise they'll follow me to the top while killing my units, which isn't very useful. When Custer and I clash together, the rest of his army will scriptedly continue walking to my town at the bottom... Doh! ;)