The Beer Hall Putsch was the first (and unsuccessful) attempt by the Nazis to seize political power in Germany (in Bavaria, actually). About two thousand Nazis marched to the center of Munich, where they were confronted by the city police which promptly and unceremoniously opened fire.
The resulting brief gunfight resulted in the death of sixteen Nazis and four police officers (Nazis had guns, too and no less promptly returned fire). The subsequent trial transformed Adolf Hitler into a nationwide celebrity and became an important stepping stone on his road to an absolute power in Germany.
So he (and the whole Nazi Party) had every reason in the world to be grateful to his fallen comrades. Consequently, there is no surprise that he listed their names on the very first page of his Mein Kampf (that he wrote while serving the jail sentence for his role in the failed coup).
Shortly after he came to power, a memorial was placed at the south side of the Feldherrnhalle crowned with a swastika. The back of the memorial read Und ihr habt doch gesiegt! (And you triumphed nevertheless!). Which was, in fact, true.
Behind it flowers were laid, and either policemen or the SS stood guard in between a lower plaque. Passers-by were required to give the Hitler salute.
Der neunte Elfte (9/11, literally the Ninth of the Eleventh) became one of the most important dates on the Nazi calendar, especially following their seizure of power in 1933. Annually until the fall of Nazi Germany, the putsch would be commemorated nationwide, with the major events taking place in Munich.
On the night of 8 November, Hitler would address the Alte Kämpfer (Old Fighters) in the Bürgerbräukeller, followed the next day by a re-enactment of the march through the streets of Munich. The event would climax with a ceremony recalling the sixteen dead marchers (regarded as the first Nazi casualties in the existential war) on the Königsplatz.
Not surprisingly, the victorious allies destroyed the Nazi Feldherrnhalle memorial. In 1994, a very different commemorative plaque was placed on the pavement in front of the Feldherrnhalle.
It contains the names of the four Bavarian policemen who died in the fight against the Nazis. The plaque reads:
“To the members of the Bavarian Police, who gave their lives opposing the National Socialist coup on 9 November 1923”