Chas wrote:Learn to kiss butt........whose ? 
 
 
Seriously from the rank of Half Colonel upwards it is
very political. Your face has to fit and you have to be
a' yes' man to the MoD and the politicians of the day.
Once you are a one star rank (Brigadier) it becomes 
even worse. From then on sadly the 'brass' keeps its
nose clean to ensure the pension and the K. At that
point the men's welfare becomes secondary and the
Generals then only make noises from the safety of 
their retirement. 

 
A bit of a jaded view. It really depends upon which army you look at, at what point in history, and in peace or war.
The Alexander the Great comparrison is a non-starter. The Greek army these days consists of better educated peasant sheep-shaggers than in wee gay Alex's day, but peasant sheep-shaggers nonetheless.
Don't forget that there are two career streams for senior officers: The command stream and the staff stream. It is possible to be a major general and not have commanded anything since a CO of a battalion. Yes, of course there is a certain political element, but that tends to be more prevalent in a peace-time army (which are few and far between these days). A more likely scenario is that those with the ability to command at higher levels continue to rise through the command stream, whereas those who reach the extent of their abilities in command, slide over to the staff stream as senior staff in higher HQ's or directorates and continue (or not) to move up through that line. The optimist would want to believe that the cream of command is rising to the top through natural selection. Of course, the reality is somewhere between that and the view quoted above. Face fitting? Yes, to a certain degree. Especially given the frequency with which said faces will appear in front of cameras these days and address issues directly related to the "party line". But those who command at the tactical level (battalion and below) have already experienced the challenge of higher command thought processes. They must, in order to properly understand the intent of their commanders one- and two-up and conduct their mission analysis correctly. But that and the true ability to focus energy at the operational and strategic levels, are two entirely different things. To properly engage the mind to function at such lofty realms requires not only advanced degrees of perception, cunning, and boldness of action, but it also demands a certain panache and finally a little luck. Even Napolean alluded to "luck" in his writings of the requisite commodities of a successful general. This "luck" is not merely for the battle field, either. Something as simple as a percieved word out of turn in front of the wrong person can set a senior offcier's career on quite a different path. But as one climbs higher (and the air becomes thinner   

 ), of course there are fewer and fewer to chose from for the very top positions. How is it then, one wonders, that so many of our "top" generals appeared either eccentric, bull-headed, sever bastards, or even utter nut-jobs? The likely truth of it is that those are mere manifestations of what it takes to function at that level with the weight of command bearing down. 
For some good insights, read up on Montgommery, or Mike Rose, or Wingate.