gjw, I speak Italian. I lived in Rome for 5 years and know very well that campaign. Anzio was a horror (and I once played a golf tournament down there). I will offer an opinion about Marc Clark though. He was an egotistical A$$. He had the chance to cut off the Germans after the French mountain troops finally breached the Gustav Line West of Monte Casino. But for the first time ever he acted on the Eureka code break information that the Germans were evacuating Rome and decided he'd be the "liberator." He never paid much attention to the signals intelligence before.
Argo, not sure how I missed your reference to "the Eureka code break". I never had anything to do with SIGINT (other than reading the reports when I had the "need to know"), but I've never heard of Eureka relative to WWII SIGINT. Are you referring to the Ultra information derived from breaking the codes the Germans used on their Enigma machines?
