Mezue ahịrịokwu na-esonụ: Mgbe Agha Obodo tiwapụrụ na 1861, von Vegesack gara United States ma sonye n'Òtù Ndị Agha Union. Ọ ghọrọ onyeisi ndị agha nke 58 nke Ohio. N'otu afọ ahụ, e buliri ya n'ọkwa onye isi n'ụlọ ọrụ General John E. Wool. O bu ụzọ jee ozi na Fort Monroe. Dịka onye enyemaka (ADC) nye Joseph K. Mansfield ọ sonyere na bọmbụ egbe egbe nke Newport News. N'afọ 1862 ọ gbara arụkwaghịm, mana mgbe ahụ ọ sonyeere Major General George B. McClellan na nnọchibido ya nke Yorktown. Dịka onye ADC na Butterfield, o sonyere n'agha nke Hanover Court House, nke
Ogwu asaa na nke Fair Oaks. Ọ nọ n'agha nke Mechanicsville, Gaines's Mill, Savage's Station, na Malvern Hill. A họpụtara Vegesack ka ọ bụrụ onye ọchịagha nke ndị agha New York nke iri abụọ, ndị agha German "Turner". E nyere ya iwu maka ndị agha nke atọ na ngalaba nke General William Farrar Smith nke ndị agha nke isii. O sonyere na Agha nke Abụọ nke Bull Run. O weghaara ugwu ndị dị n'akụkụ Jefferson, Maryland. O gosipụtara obi ike n'Antietam. Vegesack so lụọ Agha Fredericksburg. N'ọnwa Mee nke afọ 1863, ndị agha Vegesack so na ndị agha aka ekpe nke Joseph Hooker n'agha a lụrụ na Chancellorsville.