The Act of Union between Ireland and England came into operation in 1801. The latter led to the gradual adoption of the same taxes in the United Kingdom. Though Ireland was taxed separately until 1817, an adoption of the same system of taxation was achieved in the 1850s. Additionally, the Union signalled a transfer of political power from Dublin to London. My paper attempts to examine the nationalist movement in the nineteenth-century with a special emphasis on the divergence of views of the different nationalist groups and their weaknesses. Though the paper examines the evolution of Irish nationalism, it emphasises the fact that there were different forms of objection to the English authority. In this context, it tries to show that the early forms of nationalism in the nineteenth-century represented not only an objection to the Act of Union but also a defence of the Catholic interests. It demonstrates that the Irish opposition to the English hegemonic order in the second half of the nineteenth-century was mainly inspired by the radical tradition of the early physical force advocates.