[2] His first assignment was aboard the armored cruiser USS California, which participated in the 1912 United States occupation of Nicaragua.

[3] In May 1914 he was transferred to the destroyer USS Lawrence as engineering officer, participating in the United States occupation of Veracruz.

[4] In October 1916 he became engineering officer of the gunboat USS Annapolis, serving in Central American and Mexico waters.

[3] Barbey ceased to be Naval Port Officer in July 1921, but continued as flag secretary to Admiral Bristol.

[4] During this time, Barbey served as the U.S. delegate on the Allied Commission for the Control of Trade with Turkey and as an observer with the White Army in the Crimea.

He then spent two years as an inspector of ordnance at the Mare Island Naval Ammunition Depot in California, where he was promoted to the rank of commander in September 1933.

[3] In June 1937 Barbey was assigned to War Plans Section of the Bureau of Navigation in Washington, D.C. During this assignment, he worked on mobilization plans, and developed an interest in amphibious warfare from studying reports of Japanese amphibious operations in the Second Sino-Japanese War.

In 1940 he produced Fleet Training Publication 167 – Landing Operations Doctrine, United States Navy (FTP 167).

[3] In May 1942, Admiral Ernest King, Commander in Chief U.S. Fleet appointed Barbey to organize a new Amphibious Warfare Section within the Navy Department.

He established his headquarters aboard the attack transport (APA) USS Henry T. Allen on the Brisbane River and set about building up his small training command into a major amphibious force capable of carrying out the strategy of the Supreme Commander, Southwest Pacific Area (SWPA), General Douglas MacArthur, for an amphibious advance from Australia to the Philippines.

There was only one APA, the Henry T. Allen, which was in a poor state of repair and trailed an oil slick wherever it went, precluding its use in a combat zone, but VII Amphibious Force had three Australian assault transports, known as Landing Ships, Infantry (LSI): HMAS Manoora, Kanimbla and Westralia.

However half the assault troops experienced seasickness, problems were encountered with clearing the sand bar at the entrance to Guasopa Harbor, and Barbey's decision to land at night and withdraw before dawn in order to avoid encountering Japanese aircraft highlighted the inexperience of his crews and deficiencies in their training.

As the LCIs approached the beach, they were set upon by three Mitsubishi G4M "Betty" bombers which score a bomb hit and two near misses on USS LCI-339.

Major General George Wootten, the commander of the assault troops, doubted that the VII Amphibious Force could find the correct beach in the dark, and was proven correct by events; the VII Amphibious Force was not yet proficient enough to conduct night landings.

His citation read: The President of the United States of America takes pleasure in presenting the Navy Cross to Rear Admiral Daniel Edward Barbey (NSN: 0–7930), United States Navy, for extraordinary heroism and distinguished service in the line of his profession as Commander, Amphibious Force, Seventh Fleet, during attacks on Japanese-occupied Lae and Finschafen in New Guinea, on 4 September and 22 September 1943.

The sound tactical knowledge, fearless leadership and inspiring devotion to duty displayed by Rear Admiral Barbey were in keeping with the highest traditions of the United States Naval Service.

[17] Afterward, Barbey received his first properly equipped amphibious command ship, the USS Blue Ridge.

Fechteler commanded the assault on the Admiralty Islands, in which APDs were employed in order to meet the Army's requirement for a reconnaissance in force.

MacArthur told war correspondent Frazier Hunt that Barbey was "just about the number one amphibious commander in the world," but Admiral Chester Nimitz was more critical.

Skillfully building and developing an organization from men and material untried in battle, Rear Admiral Barbey succeeded in bringing the forces under his command to the high state of combat readiness within a few months which enabled them to enter upon the New Guinea operation at the peak of their efficiency.

Working in closest cooperation with associated Army Commanders and ably planning for determined aggression, he aided essentially in overcoming Japanese resistance during numerous landing operations and rendered invaluable support for forces until they were firmly established in various strategic positions in this vital area.

An inspiring and forceful leader, Rear Admiral Barbey contributed immeasurably to the success of the campaigns in New Britain, New Guinea and the Admiralties and his brilliant administration of exacting responsibilities throughout this period reflects the highest credit upon the United States Naval Service.

His citation read: The President of the United States of America, authorized by Act of Congress, 9 July 1918, takes pleasure in presenting a Gold Star in lieu of a Second Award of the Navy Distinguished Service Medal to Vice Admiral Daniel Edward Barbey (NSN: 0–7930), United States Navy, for exceptionally meritorious and distinguished services to the Government of the United States, in a duty of great responsibility as Commander of the Amphibious Forces of the Seventh Fleet, in action against enemy Japanese forces in the Southwest Pacific Area from 2 July 1944 to 1 February 1945.

Initiating a series of ably executed operations, Vice Admiral Barbey and the intrepid forces under his command effected successful surprise landings at Noemfoor on 2 July, at Sansapor on 30 July, and at Morotai on 15 September 1944, thereby establishing Southwest Pacific Air Forces within effective striking distance of the Philippines.

By his inspiring leadership and outstanding performance of duty in the planning and execution of these vital operations, Vice Admiral Barbey upheld the highest traditions of the United States Naval Service.

[1] In all, "Uncle Dan", as he was known, planned and conducted 56 amphibious operations, landing more than one million Australian and American soldiers and marines.

He briefly returned to the Far East in February 1947 as Chairman of the Joint Military Board on fact-finding mission to evaluate strategic requirements there.