In 1917, he was called to active duty for World War I, and served in the ranks in France with the 137th Infantry Regiment, part of the 35th Division.

[2] Returning to the United States in 1930, Plank was assigned to the Office of the District Engineer at Vicksburg, Mississippi from 2 October 1930 to 2 August 1931.

[6] Between 1 September 1939 and 4 February 1940, Plank attended the United States Army Command and General Staff College at Fort Leavenworth, Kansas.

The effort was made possible through decentralization, with Plank leveraging the Corps of Engineers' division and district offices, who were given permission to approve contracts of up to $500,000 and $100,000 respectively.

[10] The head of the Air Corps' Building and Grounds Division, Colonel Frank M. Kennedy, had a policy of accepting tracts of land donated by local authorities for airbase construction.

A goal was announced of expanding the Air Corps to 84 groups, fed by a training program that would turn out 30,000 pilots a year.

[13] By November 1941 the airbase construction program had grown to $708 million and was 66 percent complete, and airmen were occupying new facilities at 96 stations.

On 9 May 1942, Plank became the deputy chief of staff of the new European Theater of Operations, United States Army (ETOUSA) Services of Supply, under the command of Major General John C. H. Lee.

Plank was promoted to colonel (AUS) on 1 July 1942,[16] and on 20 August he became chief of staff of the Eastern Base Section in the UK, which, due to its relative flatness and proximity to Germany, was chiefly involved in the construction and support of airbases.

[16] Experience in Italy demonstrated the value of a logistical agency that worked closely with the army it was supporting, so in December 1943 an Advance Section (ADSEC) was organized under Plank's command; it was officially activated on 7 February 1944.

[19] Plank was promoted to brigadier general (AUS) on 24 February 1944,[20][16] and was awarded the Legion of Merit for his services as commander of the Eastern Base Section.

[22] During the period of the Allied advance from Paris to the Rhine, the Transportation Corps of the Com-Z ran the Red Ball Express to keep ADSEC and its customers supplied.

[27] When the Germans attacked in the Ardennes Offensive, ADSEC removed supplies from dumps and depots that were threatened, and supported the Third Army's counter-offensive.

[7][21] He also received foreign awards, including the Cross of Merit from Poland, Croix de Guerre from France and the Distinguished Service Medal from Greece.

[21] He then returned to the United States, where he assumed command of the Transportation Corps Training Center at Fort Eustis, Virginia.

[7][16][32][33] In retirement, Plank became the deputy director of the Department of Finance, Support and Administrative Services of the International Refugee Organization in Geneva.