The phrase "achievement of unity" is correct and usable in written English.
It can be used in contexts discussing goals, collaboration, or the process of coming together for a common purpose.
Example: "The achievement of unity among the diverse groups was essential for the success of the project."
Alternatives: "attainment of harmony" or "realization of togetherness".
Monetary unity imposed under unfavorable conditions will prove a barrier to the achievement of political unity.
The single most important issue facing the people of Ireland and Britain is the achievement of Irish unity and the construction of a new relationship between Ireland and Britain based on equality.
In addition, the singling out of half a dozen or more countries for special treatment would make the achievement of African unity, already problematical, almost impossible.
Referring to this work, Keller writes of the ease with which Britten, relatively early in his compositional career, solves "the modern sonata problem – the achievement of symmetry and unity within an extended ternary circle based on more than one subject".
Perhaps the greatest achievement -- and show of unity -- was the decision to hold the "Holy and Great Synod of the Orthodox Church" in 2016; it is to be held in Constantinople and will be both convened by, and presided over, by Patriarch Bartholomew.
Central to Fatah doctrine, however, was the firmly held notion that the liberation of Palestine was primarily the business of Palestinians and should not be entrusted to Arab regimes or postponed until the achievement of an elusive Arab unity.
Given that it was actually a short-lived and semi-nomadic school of design and art with the usual riot of individualists, visionaries, eccentrics, schemers and geniuses that such places attract, this appearance of unity was an achievement.
Creating and sustaining this mood of unity is a huge achievement for Ed Miliband.
In addition, Niebuhr was concerned that absent the required social and cultural basis for global political unity, the achievement of world government would be undesirable, since in such conditions, a world government would require authoritarian devices to rule, raising the specter of a global tyrannical power (ibid., 72 6).
