The original constitution of the modern Greek state dates back to 1844. On 1843-09-03 and following 12 years of rule by the court of the inexperienced Bavarian king Otto, a popular revolt led by veterans of the Greek War of Independence demanded representation of the people in the government. Otto gave in and the first constitution was brought into force the following year. It was based on others of the time, mainly those of Belgium and Denmark, and was one of the first in the world to provide universal manhood suffrage. It did have major weaknesses insofar as it resulted in an oligarchic system of government and virtually enshrined a corrupt system of patronage.
More reforms followed in 1864 but the major step towards a modern parliamentary republic was made in 1911. The constitution of 1927 was that of the Second Republic after the king was deposed and was followed by several autocratic civilian and military rulers. The constitution of 1952 followed World War II and the Greek civil war of 1946-9 and was a strictly conservative one which gave the executive enormous powers in a semi-functional monarchy.
In July 1974, the country emerged from the seven year rule of a military dictatorship. Constantine Karamanlis was called upon to return from self-exile in Paris and lead the new civilian government. In the referendum of 1974-12-08, Greeks voted for a republic, the monarchy having failed them and being held responsible for the junta because of the Court's meddling in government affairs--apart from simply being a foreign dynasty, the monarchy having been imposed on the country by the Great Powers after independence in 1830.
The 1975 constitution is based on the previous one of 1952 which the junta had suspended and replaced with one of its own making. The 1986 revisions centred mainly on reducing the president's powers and eliminated items essential for safeguarding the young republic in 1975 but no longer necessary after its firm establishment. As a document, I don't find it very well-written. Many articles end up being generalities, ultimately deferring to the legislative or executive.
Some of its provisions may seem obvious and self-evident but Southern Europe in the mid-1970s, much like Latin America in the 1980s, was not a place where you took democratic government or reason for granted. In some parts the constitution overcompensates for this insecurity, becoming unnecessarily verbose.
The creation of the present constitution was the fifth major constitutional change in the history of the modern Greek state, following those of 1844, 1864, 1911, 1927 and 1952. The constitution took effect 1975-07-11. Revisions were approved by sessions of parliaments specially designated to do so on 1986-03-06 (mostly limiting the powers of the president) and, more extensively, on 2001-04-17.