On April 20, 1861, a massive rally in response to the fall of Fort Sumter took place in Union Square in New York City. 100,000 or more people were in attendance, making it possibly the largest single gathering in the nation’s history up to that time. Major Robert Anderson, commander of Fort Sumter, was the guest of honor, and the flag that flew over Sumter during the bombardment was flying over the rally. One of the speakers was Edward D. Baker, fifty-year-old U.S. senator from Oregon.  He spoke eloquently on avenging Fort Sumter, and concluded with a vow that he himself would be willing to serve in the coming conflict. His speech was received with “prolonged applause.”

Edward Dickinson Baker was born in London in 1811 to Quaker parents that emigrated to the United States. His family lived in Pennsylvania and Indiana before settling in Illinois. Baker opened a law office in Springfield, Illinois in the 1830s, where he became close friends with Abraham Lincoln – in fact, one of Lincoln’s sons, who tragically died at age 3, was named Edward Baker Lincoln, or “Eddie.” Despite being friends, Baker defeated Lincoln for the Whig Party nomination for the 7th Illinois congressional district in 1844, and went on to win the seat. When the Mexican War broke out in 1846, he was appointed colonel of the 4th Illinois Volunteer Infantry and fought in the Battle of Cerro Gordo, where he assumed brigade command after the wounding of Brigadier General James Shields. After the war, he was elected to Congress again for one term, then subsequently moved to San Francisco where he opened a successful law practice. One of his law partners was Isaac Wistar, a Philadelphia native who had moved west in the Gold Rush. In 1859, Baker moved north to the new state of Oregon to campaign for one of its open Senate seats. He was elected by the Oregon legislature as Senator in October 1860, and took his seat in December just before South Carolina seceded.

The day after the rally, a meeting was held at the Metropolitan Hotel in New York City for Californians, Oregonians and anyone else from the Pacific Coast to organize a military unit to be known as the “First California Regiment.” Senator Baker, as a prominent man with ties to the West Coast, was invited to this meeting and gave a speech (despite being hoarse from the previous day’s rally). Baker was unanimously elected as colonel of the nascent unit, and promised he could raise 800 men from New York City to fill the ranks of this new regiment. Planning and preparation began to house, equip, and train the California Regiment in New York City. Upon Baker's return to Washington, President Lincoln gave Baker unofficial permission to raise the California Regiment. Baker then met with Isaac Wistar, his old law partner who was now a lawyer in Philadelphia and an officer in the Pennsylvania militia. Baker asked Wistar if he could raise the regiment from New York in thirty days, but since Wistar didn’t really have any connections in New York, he suggested raising the men in his native Philadelphia instead. Baker agreed, so long as the men were then sent to New York where they would be mustered into federal service and trained. Within several days, hundreds of men were on their way to New York from Philadelphia to join the California Regiment.

On May 8, 1861, Baker received formal permission to raise the California Regiment from the War Department. The following day, the 700 new recruits of the California Regiment that had mostly been sent from Philadelphia were sworn in to federal service for three years. The regiment spent most of June drilling and training at Fort Schuyler in the Bronx.