Mezue ahịrịokwu na-esonụ: Mackie sonyere ndị agha mmiri site na New York na Eprel 24, 1861. Ebe mbụ e kenyere ya ọrụ bụ n'Òtù Ndị Agha Mmiri n'ụgbọ mmiri USS "Savannah". E buliri ya n'ọkwa onye isi n'ụbọchị mbụ nke ọnwa Machị n'afọ 1862. N'April 1, ọ malitere ije ozi n'ụgbọ agha agha USS "Galena". Na May 15, otu ụgbọ mmiri ndị agha mmiri nke Union, gụnyere "Galena", gbagoro n'osimiri James iji nwalee nchebe nke isi obodo Confederate, Richmond, Virginia. Mgbe ha rutere n'akụkụ osimiri nke dị n'elu Dutch Gap, ndị agha ahụ zutere ihe mgbochi na nnukwu ọkụ site na battalion abụọ nke ndị agha Confederate Marines nọ n'akụkụ osimiri na ọkụ ọkụ site na Fort Darling n'elu Drewry's Bluff ihe dị ka kilomita asatọ n'okpuru Richmond. Mackie duziri ndị agha mmiri iri na abụọ n'ebe a na-edebe ngwá agha. Ngwongwo ndị agha nke ebe e wusiri ike mebiri "Galena" nke ukwuu ma mee ka ndị agha nke Union laghachi azụ. N'oge a na-alụ agha ahụ (nke a bịara mara dị ka Agha Ụwa nke Abụọ)
N'agha nke Drewry's Bluff), ihe ka ọtụtụ n'ime ndị ọrụ ụgbọ mmiri Galena nwụrụ ma ọ bụ merụọ ahụ. Mackie duziri otu ndị agha mmiri bụ ndị weghaara ọrụ nke egbe ruo oge fọdụrụ n'agha ahụ. N'abalị mbụ nke ọnwa Nọvemba, e buliri ya n'ọkwa sergeant. N'ọnwa Juun nke afọ 1863, e zigara ya n'ọchịchị.