Tens of thousands joined peaceful marches through Greece's two biggest cities Sunday to commemorate the 40th anniversary of a bloody student uprising against the then dictatorship.

Previous marches had been marked by riots and running battles between anarchists and riot police, but this year's commemoration went off without incident, partly thanks to heavy police presence. In Athens, 9,000 police were deployed and 99 people were detained provisionally before the start of the marches.

According to generally conservative police estimates, about 10,000 mostly leftist, anarchist and union supporters joined one march in Athens and a similar number of Communist Party supporters marched separately. In the northern city of Thessaloniki, an estimated 13,000 have turned out, with no incidents reported.

Both marches in the capital ended outside the U.S. Embassy, about 3.5 kilometers (2.2 miles) from the National Technical University of Athens, widely known as the Polytechnic, the center of the 1973 revolt. Most Greeks still blame the U.S. for supporting the 1967-74 military regime.

The revolt was crushed when a tank stormed through the university's gates in the early hours of Nov. 17, 1973. The number of fatalities is still disputed; at the time, the regime had announced 15 dead.

A prosecutor's report issued the following year, after the return to civilian government, estimated fatalities at 34, but mentioned only 18 names. There were over 1,100 injured.