During the early 17th century, Tullamore was a small village of 200 people and did not play a significant role in the history of Offaly until after the plantation of counties Laois and Offaly. Due to the influence of the Moores who lived in Charleville, a military garrison was placed in Tullamore which expediated growth as the population and economic activity developed to service this garrison.

In 1765 ownership of Tullamore and 20,000 acre estate passed to Charles William Bury, who was responsible for much of Tullamore's growth. In 1785 a fire caused by a hot air balloon destroyed much of the town and facilitated its orderly development. The arrival of the Grand Canal in 1798 eventually connected Tullamore to Dublin and rivers of the Shannon and Barrow. In 1835 Tullamore became the County Town of Kings County (Offaly).