Drogo's army destroyed that army of another Khal, that alone should be evidence of military skill/cunning... yes he was brought low by Dany's foolish compassion for a conquerord enemy, when you consider that Drogo was initially opposed to being treated by the woman, it shows Drogo's failing was loving his wife too much and acceeding to her will, and not having a jaded perspective. Look I can't tell you what Drogo coulda or woulda done had he survived I can only tell you that Drogo had all the makings for achieving GREATNESS
Well that would imply the Dorathki actually used Tactics, which they didn't
They had no unit structure, like the Huns or Mongols.
They had no combined Arms tactics.
No understanding of advanced tactics.
How long do you think 3,000 Unsullied would have lasted against Huns or Mongols?
No the Dorathki charged them, when that didn't work they charged them again and again, fired a few thousand arrows and repeated it.
Drogo's victory over another Khal, which RR seems to think makes him Drogo the Great, could have been won by Custer or Hitler.
Charging an enemy in the process of looting a city with vastly superior numbers is not exactly the Battle of Cannae.
OH yes and for being held as the major military force in the region is not suprising, given their opponnents. Mercs, Slaves and Lamb People. Then the point they always outnumber their opponnents by a helluva alot.
Had Viserys and his 20,000 invaded Westeros they would have lost.
Had Drogo and his 40,000 invaded Westeros they would have lost.
Since some of you are going to argue if I just leave it at that I will explain.
Ignoring Viserys cause he was just pathetic and would probably have sailed past Westeros and invaded somewhere else.
Why would any Westeros House support Drogo for the Iron Throne? Because thats who would have gained the throne, not Dany. Drogo could not have let Dany command him without losing face with his Dorathki and probably losing them.
So no Allies for Drogo and his broodmare. So all landing grounds are hostile.
Land in Dorne and get bled to death in the Deserts while taking the Castles, then if somehow they manage to win have to fight their way out through the Bottlenecks in the Mountains of Dorne. Likely straight into the combinded forces of Tyrells/Baratheons with maybe the other 4 aswell.
Land in the Stormlands and He would have to take several very nasty Castles (Storms End held off a massive Tyrell Army) and would lose men everytime, while reinforcements pour into the Stormlands from North, West and South.
Land around King's Landing, except you have to take Dragonstone (losing men) or risk getting Stannis's warships up your arse while the Royal Fleet slams into your face, massive losses at sea if the big War Gallleys get among the Transports. Then more taking King's Landing and likely end up getting attacked from all directions by the reinforcements.
Land in the Vale, get bled taking it and then have to fight out through more Bottlenecks which are VERY bad things for Mobile Armies.
Land in the North get bled taking and then have to fight out down one road while being shot stupid with poisoned arrows.
Can't Land in the Reach because the Redwyne Fleet would smash you, while the Royal/Stannis's fleets come from behind.
Rest of the West Coast has the two biggest Fleets protecting it.
So you can't land without massive casualties and more then likely end up stuck in one Kingdom.
Nice just bring in more men, oh wait he doesn't have access to reinforcements.
It be like trying to fight the Normandy campaign with nothing but the intial invasion troops.
I don't care how good you think the Dorathki are, no way in hell 40k Dorathki could take 200k Westeros with more men waiting in reserve.
a Dorathki Army in Westeros would be bled to death before it got much done.
I doubt they would even get across the Narrow Sea, I am sorry but even Cersei would know some guy was getting enough Transports and Escorts to ferry 40k men across the Sea.
By far enough time to bring the Redwyne and Likely Iron Fleet around, heck could probably attack them at the embarkation area before they were ready.