Jacob Kane was born in 1898, the oldest of two children of the Kane family, an old money Gotham family with a rich military history (supposedly dating back to the American Revolution). Kane spent much of his early years struggling under the immense pressure to live up to his family name. He eventually found his stride as he signed up for the American Expeditionary Force and shipped off to the Western Front in 1916. It was here that he first met Thomas Wayne.

Though he would regret it for some time, Jacob was the one to invite Thomas to the ball wherein Thomas first began to court Jacob's younger sister Martha. Following their marriage Jacob distanced himself from his sister, focusing on his college studies so that he could obtain a commission in the U.S. Army. He would eventually return to Gotham City following the death of his sister, and after a lengthy legal battle would gain legal guardianship over his nephew Bruce Wayne in 1929. Not exactly a business expert, Kane placed Bruce's inheritance into a safe, ironically saving Bruce's fortune from complete destruction during Black Tuesday (the beginning of the Great Depression).

Kane was distant, although a much better guardian than Thomas had been. Still, he didn't know how to help Bruce cope with his grief, and instead used his family money to let Bruce do pretty much whatever he wanted, allowing Bruce to travel the globe and learn many tricks. Jacob would be drafted into the U.S. Army during their entrance into World War II, rising to the rank of Major General before dying of dysentery in the Pacific Front in 1944.