The land of the township was first settled by Europeans in 1835, and the first permanent settlements by Europeans were built in 1836, and the first house was built by a settler named William Fenwick on the south side of Diamond Lake. The first post office named was established in the township was in 1839 between Half Day and McHenry, until it was disestablished in 1842. The post office was named after its postmaster, Charles Darling.[1]
In 1837, a settlement inside the township was called "Fort Hill Settlement" after a prairie hill in the northwest of the township, and would establish its post office in the spring of the following year.[1]
The first church established was the Fremont Congressional Church on February 20, 1838, halfway between Ivanhoe and Mundelein. The church initially was made up of sixteen members, twelve of which were from Hartford, New York. The church was initially Presbyterian but would change denominations to Congregationalism in 1844. A Catholic Church would be established three years later in 1841 named St. John's Roman Catholic Church. in the 1850s, a Methodist Episcopal Church in Diamond Lake and a German Catholic Church south of Fremont Center would be established.[1]
A vote was held to decide the name of the township on January 12, 1850. While the name of "Gilmer", from the Secretary of the Navy at the time Thomas Walker Gilmer, won the plurality of the votes, it failed to reach a majority of the votes required to adopt the name. "Fremont" was chosen as a compromise name after the explorer and future presidential candidate John C. Frémont. The first town meeting for the township was held the same year. The first supervisor appointed was Hurlburt Swan, a man from Connecticut who also served in the Illinois General Assembly. During the American Civil War, over 120 people from the township enlisted for the military, killing 34 during the conflict.[1]
Fremont Township covers an area of 35.8 square miles (92.8 km2); of this, 1.7 square miles (4.4 km2) or 4.69 percent is water.[2] Lakes in this township include Countryside Lake, Davis Lake, Diamond Lake, Lake Fairfield and Schreiber Lake.
The median household income of the township was $114,916, above the median household income of Lake County. The poverty percentage was 4.2%, below the 8.0% of Lake County.[3]
