"forced illiteracy by the Church"?
What year did this happen?
Ruling of the Council of Tarragona, 1234 CE: "No one may possess the books of the Old and New Testaments in the Romance language, and if anyone possesses them he must turn them over to the local bishop within eight days after promulgation of this decree, so that they may be burned..."
Decree of the Council of Toulouse, 1229 CE: "We prohibit also that the laity should be permitted to have the books of the Old or New Testament; but we most strictly forbid their having any translation of these books."
The Council of Trent (1545-1564 CE) placed the Bible on its list of prohibited books (!!!), and forbade any person to read the Bible without a license from a Roman Catholic bishop or inquisitor. "That if any one shall dare to read or keep in his possession that book, without such a license, he shall not receive absolution till he has given it up to his ordinary."
In what country did this happen?
In any country controlled by the Church.
Was it nationwide?
It was wherever the Church was
Did it happen in all European countries?
Wherever the Church was in control.
When did it end?
For the next 1200 years, Christian clergy pursued a policy of establishing a soft monopoly on Bible reading and a hard monopoly on its interpretation. After all, a simple mind could misunderstand the word of God, right? A key element of this policy was that Bible translations were forbidden - this created a natural boundary that kept lay readers out of the word of God.
The Catholic Church continued to frown on lay Bible readers for some centuries to come. The Reformation movement disagreed, taking particular issue with this. For many groups of reformists, Sola Scriptura (scripture only) was a cornerstone piece of doctrine, and thus all the faithful were required to read the Bible. But that only happened in the 16th century.
Did it really not happen at all?
The whole education system was designed to keep serfs and peasants uneducated; indeed, education during that time was very elitist. Study books were very rare and they were highly expensive and hence, the only way to get education was to seek a teacher.
Officially, you needed a "trained" mind to properly interpret the Word of God.
Less officially, it gave the clergy an aura of secret knowledge and authority. I know the word of god, and you do not - that is a powerful claim. The Church of Scientology currently does the same thing - restricting access to its "secrets", only uncovering them as you progress through the ranks.