[BroJoeK]

JOHN ADAMS: "As I recall, they had the high ground and enough time to have entrenched themselves and their weapons effectively before they were attacked.
Frontal assaults on entrenched positions have been at least a risky idea, and often a bad idea, since at least early July, 1863."

Bull Snipe: "since 1862.
Lee launched a frontal assault up hill against the AOP at Malvern Hill.
The results were exactly the same as at Cemetary Ridge, lots of casualties and nothing to show for the price paid."

I think I remember two other famous battles whose victory was based on failed frontal assaults up hill against troops at least hidden, if not fully entrenched:

At Waterloo in June 1815, Napoleon's troops marched up the hill against British troops hidden (laying down) just beyond the ridge.

But even before that, and before Stonewall Jackson was even born, there was Colonel Jackson:

"In 1814 we took a little trip
Along with Colonel Jackson down the mighty Mississip
We took a little bacon and we took a little beans
And we caught the bloody British in the town of New Orleans...

"We looked down the river and we seen the British come
And there must have been a hunnerd of 'em beatin on the drum
They stepped so high and they made their bugles ring
We stood beside our cotton bales 'n' didn't say a thing..."

"Old Hickory said we could take 'em by surprise
If we didn't fire our muskets till we looked 'em in the eye
We held our fire 'till we seed their faces well
Then we opened up the squirrel guns and really gave em…
Well we..."

So maybe it was that Lee needed less Stonewall and more Old Hickory?

[Bull Snipe]

Lee assault on Cemetery Ridge was a last resort effort. Lee knew it was a risk. Lee’s victories, except Fredericksburg, came with taking risks. His decision concerning the objective of the entire Pennsylvania campaign was to defeat the AOP by attacking them. Not sitting on a hill waiting to be attacked.
In this regard, Lee’s thinking about the value of the offense in battle was identical to Grants.