It's a memorable day in world history. What happed on that day for that reason it become the international mother language day? Some people have the question. Most of our young genertion don't know the history of that day. As a bangaladeshi each and every person must know the history, also we should let to know that history of our young generation. Only bangaldeshi sacrificed their life for language.
Its a long history but i will discuss only the incident of 21st february in brief. This history start from 1947 when india & pakistan got independence from Great Britain and become two different state. In Pakistan there are two state, East pakistan ( present Bangladesh) & West Pakistan ( Present Pakistan). In that time economical, political everything controled by West pakistan. East Pakistani people always subjugated by west pakistani people. There were lot of incident and people of East pakistan make clique to raise voice anginst west pakistan.
In the language movement on 20 february1952 Pakistan governor Muhamad Ali Jinnah announced that Urdu will be the main state language in Pakistan where more than 4 crore people in east pakistan were speaking in bengali. After this announcement present student, teacher, journalist & others instantly raise their voice against decision. "Rastro Vasa songram parishad" commitee & other commitee decided to strike (Hartal) on 21 february. Government imposed section 144 in Dhaka city on that day also. The commitee, students and people decided violate section 144, as a result government afraid and imposed police in street.
When peoples were violating section 144, police couldn't control the rout and fired upon them. Many of students included Salam, Rafiq, jabbar died there. Then temporary concrete was created named as "shaheed Minar (Martyrs Memorial)" on respect to the Martyrs of that day.
In 1956 Pakistan decleared that both Bangla & Urdu state language of Pakistan. Since 1952, 21 February observed as Mother Language day. On 17 Nov 1999 UNESCO decleared 21 February as international Mother language day.
Thanks for reading the post. I have written as I know. If you want to know the details then need to read history books.