Rubuta ci gaba ga wannan sakin layi - Grindlay ya shiga daga Boonville a ranar 8 ga Satumba, 1862 don tsawon shekaru uku na hidima a rundunar sojojin Union. Ya shiga Kamfanin D na 146th New York Infantry a matsayin kyaftin. A watan Mayu da Yuni na 1864 rundunar ta shiga cikin Janar Ulysses S. Grant na Kamfen na Overland a Virginia. A yakin Basasa a makon farko na watan Mayu, 146th ya yi mummunan rauni. Dukansu kwamandan kwamandan da na biyu a cikin kwamandan sun mutu a cikin aikin, suna barin Grindlay a matsayin babban jami'in. Ya dauki umurnin rundunar kuma ya jagoranci ta ta hanyar yakin Spotsylvania Court House wanda ya biyo baya. An gabatar da shi zuwa babban, Grindlay ya jagoranci 146th don sauran yakin, ciki har da yakin Arewa Anna, Totopotomoy Creek
, da kuma Cold Harbor.