The fact is that the US Army ended up fighting 1943 vehicles (Panzer IVlong/StuGlong/Panther/Tigers) in 1944. They brought 1942 class vehicles. They had previous knowledge of the enemy AFV before D-Day. They faced another wave improvement (Hetzer/Jagdpanzer) also. It really does not matter when a design is started, it matters when it is fielded. So this statement...
The point being, which I'll state again, that all the armies in Europe were using equipment in 1944 that had been the result of combat experience in 1942. This isn't a revelation to anyone.
...is just wrong.
No, in fact it isn't. And were you a little more aware of the development cycle of any the vehicles you mentioned you might realize that? Or of what the Allies "knew" prior to D-Day.
Pz-IV (l) was a 1937-era
vehicle, its adaptation to the KwK 40 L-43 and later L48 was anything but simple, and the result overstressed the suspension, drivetrain, and chassis, probably materially leading to the low readiness rates found in it. And the concept began in July-August 1941, with a prototype completed in November and first production in April 1942, getting in the hands of troops around July. And those were complete factory builds
they were not depot modifications. StuG-III (l) was similar.
Similarly the Tiger I antecedents lead back to September 1938 and a design order of May 1941, production didn't begin until well over a year later.
Nor was Hetzer an "improvement" it was a desperate attempt to maintain the usefulness of a production line incapable of producing more modern vehicles. Which is also something similar to the story of the JgPz-IV.
What matters is design, production, and fielding.
And, as far as the Panther goes, the first complete Allied technical assessment of a Panther was dated 6 June 1944. How many Allied tankers do you think were reading it while crossing the Channel?
They certainly had people within the US Army that wanted 90mm guns BEFORE D-Day. It was shot down by the clowns in charge. So they landed with old-school 75mm AFV and also light tanks with 37mm. The wonder-gun 76mm arrives soon and is seen as a mistake. The whole time-table gets shot to hell and they burn up artillery ammo like it can not be delivered fast enough.
Really? You should be able to tell us all then who these "clowns" were and exactly what they "shot down" and when? And exactly why the 76mm was a "mistake"? And what "time-table" got messed up and why that resulted in excess artilery consumption?
So up-gunning M5 chassis to carry 57mm, putting 90mm weapons into something like a M7, mounting PAK40's on chassis much like a Marder, should have been done.
M5 and 57mm, sorry, doesn't fit, I'm getting a bit tired of repeating it. so maybe I won't get tired of retracting it? The M8 HMC Modified does at least show that the idea might have been feasible, but it still doesn't show it was a good idea, especially at a time when what was needed was more medium tanks?
90mm in an M7 - been there, done that, not a real workable idea really, and you need to find 90mm guns for them (oh, wait, let me fill in your next line for you "well, gee willikers, they didn't need any antiaircraft guns so the would have known there was plenty if they had just been as smart as me"). Instead they put them in a slightly more finished design, the M36.
Why would the US Army want to mount Pak 40's on chassis like Marders? But if you want Marder-like designs from US Army Ordnance with a Pak 40 equivalent, there were quite a few, but they were replaced almost immediately by a batter "tank-like" version, the M10.
In retrospect, perhaps the Americans were better off in the hedgerows? What if the allies had all chose to come ashore in open country?
Is that meant as a non sequiter?
But my premise is that the US should have at least field modified some vehicles to carry better weapons. The promise of Pershing Tanks (is that correct? yep, in 1948) and M24's for all, did not come soon enough. The 37mm class weapon was dropped from most armies by 1944. Its HE was a joke (base-fuze) and AP out-classed. To think that cav units were going to blaze a trail with this gun (in M8 armored cars and M5 tanks) was delusional. If you have read the cav units tactics, the way they were supposed to use the vehicles, you might be surprised. A buddy of mine's father was in the 4th armored and was in the cav. They drove around with 'one-foot-out'.
Methins you have been reading a bit too much of the Screed Belton? Which, don't get me wrong, is a great memoir and he was a wonderful guy - I met him - but as a history of the development and fielding of US Army tanks in World War II it falls a bit short. The vissicitudes of US Army tank development and production were many and very complex, believe me, I've been trying toi write the book for a while and have barely scratched the surface.
So where exactly was it said that mechanized cavalry was to "blaze a trail" by fighting for it?
"MISSIONS.-a. The principal mission of the reconnaissance squadron is to obtain the information required by
higher authority and get it back to the interested commander in time to be evaluated and acted upon.
b. While the squadron is capable of executing counterreconnaissance and certain offensive and defensive operations,
the division commander, before assigning such other missions, should consider the availability of other troops more
suitable to perform them and the relative importance of the missions compared with reconnaissance." (FM 2-30, Cavalry Field Manual: Cavalry Mechanized Reconnaissance Squadron, 29 March 1943)
"3. MISSION. The cavalry reconnaissance troop, mechanized, is organized, equipped, and trained to perform reconnaissance missions. Other types of missions are given only in the furtherance of a reconnaissance mission of the troop or the squadron of which the troop is a part, unless no other troops are available for other types of operations for the division or other larger unit. Reconnaissance missions are performed by employment of infiltration tactics, fire, and maneuver. Combat is engaged in only to the extent necessary to accomplish the assigned mission." (FM 2-20, Cavalry Reconnaissance Troop Mechanized, 24 February 1944)
The cavalry was never intended as an offensive arm by itself, and there were real concerns that arming them too heavily would distract them from their primary mission, a debate about reconnaissance that continues to this day.