Yes, the whole use of longbows as attack units with Drill IV has blown out of proportion.
Originally all I wanted to demonstrate was that Drill IV
could be used even on offense, and even with a unit as unlikely as a longbow.
The use of longbows is actually strongest, like with almost every unit in the game, when it is leading edge in technology. Before anyone has maces, longbows are very competitive even as attack units, but particularly as defenders.
I may have put too much emphasis on the drill promotions. There are many cases where combat beats them by a small or moderate margin, but I just remind myself PRO has other bonuses which can be taken advantage of...
I still maintain in the vast majority of games, PRO is the only trait that makes the drill line worth trying at all.
What I will leave finally in this post, is this picture from a game many months ago. After I had captured an American city, I found Washington kept sending waves of units at me. I had two longbows defending the new city, and one of them had CG1, Drill IV and C1 (in the picture the C2 came from an upgrade on the current turn). Facing this attack wave, it single-handedly took down 5 catapults, 2 swordsmen and 1 horse archer. It must have taken a hit or two from the horse archer because after that the next longbow stood up and took place in defending the city. The next one was less promoted I think, and it died to the next horse archer.
In this example, the advantage in strength coupled with the first strikes made that longbow an unbelievable cit defender. Also, note how much xp it has now.