William Grimshaw was admitted to the bar in Philadelphia, Pennsylvania, and came to Pike County in 1833. A prominent local attorney, he served as adjutant of the 17th Illinois Militia and was a delegate to both state constitutional conventions as a Whig Party member. He authored the provision against dueling in the 1847 state constitution. Grimshaw participated in several court cases with Lincoln in Pike County and hired Lincoln to represent him in a federal court case in Chicago. Grimshaw's office was in one of the front rooms of his home. He was a delegate to the Republican National Convention in Chicago in 1860, which nominated Lincoln for President.