Killing, yes. Absolutely tragic but not senseless, at least not from the standpoint which already recognizes that war itself is a horrible tragedy. Not senseless from the standpoint that the vast majority of weapons were still single-shot: to mass fire
did still mean massing men for an attack - which commanders almost always sought to combine with some kind of flanking maneuver (or overwhelming with artillery first or numerical weight when possible &c). I guess that's one of my difficult topics: the ACW is often described as an unprecedented conflict in scale, losses, lack of tactical acumen, lack of appreciation for the rifle, and the rest. I'll grant that it must have seemed like that to contemporary Americans who were seeing war on the European scale for the first time, but I feel like historians should know better.
(Not (at all!) meant to pick on you, Billy Yank

. It's been a common theme since the days of T Harry Williams and I sometimes wonder why it persists. And I'm willing to consider that maybe Paddy Griffith and Brent Nosworthy have brainwashed me a bit, too...

)