In my book – The Generalship of Ulysses S. Grant – I pointed out that, in 1861, the average age of twenty Federal and Confederate officers who, as generals, played leading parts in the war, was thirty-eight and a half years. [...] In war it is almost impossible to exaggerate the evil effects of age upon generalship, and through generalship on the spirit of an army. In peace time it may be otherwise, but in war time the physical, intellectual and moral stresses and strains which are at once set up immediately discover the weak links in a general’s harness. First, war is obviously a young man’s occupation; secondly, the older a man grows the more cautious he becomes, and thirdly, the more fixed become his ideas. Nothing is more dangerous in war than to rely upon peace training: for in modern times, when war is declared, training has always been proved out of date. Consequently, the more elastic a man’s mind is, the more it is able to receive and digest new impressions and experiences, the more commonsense will be the actions resulting. Youth, in every way, is not only more elastic than old age, but less cautious and far more energetic.From Nathaniel Hawthorne's article "Chiefly About War Matters":
(Wool would have been 78 during Hawthorne's visit.)
p.s. Of related interest...
General Wool writes a letter
Generals who faint
"Why senior military leaders fail"
And for a blow-by-blow account of Wool's machinations against McClellan during the first Richmond campaign, see the most recent volume by the late, great Cap Beatie.