Ah, the learning curve was huge and unfortunately cost many, many men their lives. This kind of thing ocurred in North Africa too. This was still a fairly new venture gaining beacheads and landing men behind enemy lines for invasions. The Army and the Navy were still pretty inexperienced with this, and as you know some of these initial landings were anything but smooth.
It is very hard to read about all the SNAFU's that occured in the early days of the war. Thank God that lessons were learned in the later campaigns. But with things of this nature, the only way to learn is through doing. God Bless all the men who lost their lives this way.
Since we are only talking of the ETO here, people should also be aware of the huge loss of life that occured in other landings such as in the Pacific Theatre. While there are many, Tarawa always comes to mind. A lot of men drowned while trying to take this beachhead and never even made it to shore. 
It was also at Tarawa that the battleships learned the lesson that they needed to be about 10 miles offshore in order to have their big guns be effective. The shells were exploding above ground and basically did nothing to destroy the enemy that had their defenses buried deep. While offshore it appeared that the enemy was getting the hell blasted out of them, the marines that landed on shore found out otherwise.
Proud Daughter of Walter (Monday) Poniedzialek
540th Engineer Combat Regiment, 2833rd Bn, H&S Co, 4th Platoon
There's "No Bridge Too Far"