By this, I'm guessing your Dad was in the 3rd Infantry Division and not the 3rd Armored:
http://en.wikipedia.org/wiki/3rd_Infantry_Division_(United_States)
Combat operations
The 3rd Division is one of the few American divisions that fought the Axis on all European fronts and was among the first U.S. combat units to engage in offensive ground combat operations during World War II.
The Division first saw action as a part of the Western Task Force in the North African invasion, landing at Fedala on 8 November 1942, and captured half of French Morocco. Eight months later, on 10 July 1943, the Division made an assault landing on Sicily, fought its way into Palermo before the armor could get there, and raced on to capture Messina, thus ending the Sicilian campaign. Nine days after the Italian invasion, on 18 September 1943, the 3rd landed at Salerno and in intensive action drove to and across the Volturno River and to Cassino. After a brief rest, the Division was ordered to hit the beaches at Anzio, 22 January 1944, where for four months it maintained its toe-hold against furious German counterattacks. On 29 February 1944, the 3rd fought off an attack by three German Divisions.
In May the Division broke out of the beachhead and drove on to Rome, and then went into training for the invasion of Southern France. On 15 August 1944, another D-Day, the Division landed at St. Tropez, advanced up the Rhone Valley, through the Vosges Mountains, and reached the Rhine at Strasbourg, 26 27 November 1944. After maintaining defensive positions it took part in clearing the Colmar Pocket, 23 January, 18 February 1945, and on 15 March struck against Siegfried Line positions south of Zweibrücken. The Division smashed through the defenses and crossed the Rhine, 26 March 1945 ; then drove on to take Nuremberg in a fierce battle, capturing the city in block-by-block fighting, 17 20 April. The 3rd pushed on to take Augsburg and Munich, 27 30 April, and was in the vicinity of Salzburg when the war in Europe wound down.
Elements of the 7th Infantry Regiment serving under the 3rd Infantry Division had the honor of capturing Hitler's retreat at Berchtesgaden.[2]
The 3rd Division suffered more combat deaths in World War II than any other U.S. division, and the third highest among modern U.S. Divisions, behind only the 2nd Infantry Division in the Korean War and the 1st Cavalry Division in the Vietnam War.
You may want to check the "Society of the 3rd Infantry Division, U. S. Army" site:
http://webcache.googleusercontent.c...ision,+Caserta,+1944&cd=3&hl=en&ct=clnk&gl=us
This link will give some info but not where a soldier served:
World War II Army Enlistment Records, created, documenting the period ca. 1938 - 1946
http://aad.archives.gov/aad/display...=V,2,1900&op_24983=0&txt_24983=&mtch=106&pg=2