According to Chester Wilmont's fantastic The Struggle for Europe, in the summer of 1944 (Map: The Mediterranean Front, Summer 1944, p.451) The U.S Fifth Army and the British Eighth Army under Generals Clark and Alexander were located in Italy at the time. The French First Army was utilised as part of Operationa ANVIL.
This is actually an interesting story. Roosevelt was pressing for an invasion of Southern France rather than a push into Central Europe via North Italy, despite the obvious strategic benefits, because he wanted to appease Stalin. Marshall also was a major supporter of Anvil, presumably because he was grossly incompetent. Wilmont writes:
But when the time came to employ those forces in the field, Marshall
had neither the strategic insight nor the operational experience to
guide his judgement. His ideas were simple and rigid.
Stalin opposed the idea because of the implicit agreement that the nations who liberated countries would be permitted to impose their ideology upon them.
Churchill was (quite rightly) afraid of Soviet domination of Eastern Europe, wished to capture the Balkans before the Soviets could arrive. He and his staff also questioned the necessity of ANVIL given that the Germans would need to withdraw from southern France after OVERLORD anyway (which they did).
Churchill (as well as Clark and Alexander) were proponents of a renewed Allied offensive north into Central Europe and on to Vienna, partly because it would have prevented Soviet occupation of much of Central-Eastern Europe, and that it would likely have brought a swifter conclusion to the war, as it would have put the Allies within striking distance of the Germans main source of oil at Ploesti.
However, since Marshall held the "purse strings" (Landing Ship Tanks and other logistical resources) and Roosevelt was naive enough to believe that Stalin would conform to his idealistic view of a post WW2 utopia, ANVIL took place instead. Eisenhower, paranoid about the Germans sealing off the Normandy beachead also wanted to hedge his bets with a landing in Southern France - a critical mistake since if they weren't able to beat the Germans in Normandy, landing there would be a grevious error and attack from Italy would have acieved better results anyway. However Eisenhower desired additional ports in Southern Italy to hedge his bets.
Alexander lost seven divisions to Anvil just as, Wilmont puts elegantly
" The threat to the strategic centre of Europe was thus relaxed just
when it was assuming serious proportions...
Hitler was spared the critical necessity of having to reinforce his
southern flank at the critical juncture when he was hard pressed to
the point of desperation both in the West and the East."
In his book, Calculated Risk, General Clark states :
A campaign that might have changed the whole history of relations
between the Western world and the Soviet Union was permitted to fade
away, not into nothing, but into much less than it could have been ...
Not alone in my opinion, but in the opinion of a number of experts who
were close to the problem, the weakening of the campaign in Italy in
order to invade Southern France, instead of pushing on to the Balkans,
was one of the outstanding political mistakes of the war ... Stalin
knew exactly what he wanted in a political as well as a military way;
and the thing he wanted was to keep us out of the Balkans ... It is
easy to see, therefore, why Stalin favoured ANVIL at Tehran.
So in Answer to your question - the British 8th Army and the U.S Fifth Army occupied the Italian front in 1944, with the French First Army being deployed as part of Operation Anvil.
Source: Wilmont, Chester, The Struggle for Europe, 1952 http://www.goodreads.com/book/show/419010.The_Struggle_for_Europe
