The foreign policy of Greece during the 19th century had to face a complex international situation, which kept changing at such a pace and in such a way that Greece, being small, could not possibly always follow, let alone shape it according to its wishes or interests. The country usually had to succumb to the plans and choices of others.

During the 19th century, foreign policy in Greek political life constituted the main factor shaping internal policy, because Greece was bound by the guardianship of forces which did not miss any opportunity to interfere decisively with the regime, governance and political life of the country. The new state's territory included only a proportion of the 1821 rebels, and a much smaller number of the Greek Orthodox peoples in general. Liberation was the central political axis of the new state; setting free the enslaved compatriots was considered a 'natural order' and a religious obligation, whereas the issues of foreign policy frequently motivated many people who took action in favour of an expansionist policy, even if that was unfeasible. Finally, foreign policy was the touchstone for royalty and the politicians; it could legitimize people, institutions, ideologies and practices.

The gap between what was desired and what was feasible is typical of Greek foreign policy in the 19th century; the distance between the goal and the preparation for its achievement; the distance between dreams and reality. Over everything lies the Greeks' high opinion of themselves; the high opinion of their descent, of their mission; the Great Idea showed the way for Greek foreign policy over three-quarters of a stormy century.

In order to follow the facts relating to foreign policy, the actions of diplomacy, treaties and military action, one has to take into consideration many other aspects: institutions, and the political, diplomatic and legal framework in which they were found; the people and the roles they had to play, the discourse which developed either through texts or public action in general.