Commercial Union was established following a conflagration near London Bridge in 1861, known as the Great Tooley Street Fire, which destroyed a number of warehouses and wharves along the River Thames as a result of which the fire insurance companies were hit by a series of massive claims. Consequently, they increased their fire insurance rates so dramatically that a group of local merchants and brokers decided to form their own company. This became known as the "Commercial Union Assurance Company Ltd."