Some 650 former inmates of the camp took part in the commemoration ceremonies on Sunday, during which Koehler called Dachau an important reminder of Germany's darkest period.
Before giving his speech, Koehler laid a wreath at the site of the former crematorium. He is the first German president to visit the memorial, located near Munich in southern Germany.
Camp model
Dachau was set up in 1933 and was the only camp to operate for the entire 12 years of the Nazi regime.
It also served as a model for other camps later constructed across Germany and in countries occupied by Nazi forces.
The first inmates at the camp were political prisoners, but soon Dachau also held Jews, Sinti and Roma, gays and people classified as "asocial" and "criminal" by the regime.
In total some 200,000 people from across Europe were held at Dachau - more then 43,000 people died or were killed at the camp.
When US troops arrived on April 29, 1945, they found around 32,000 prisoners.
Two decades after its liberation, the site became a memorial thanks to the work of surviving inmates. The memorial and museum receive around 700,000 visitors each year.
DW World
