Check American History and you will find that patriotism was defined and consisted of far different practices than occurred following World War Two.
It was President Franklin Delano Roosevelt, an American leader the right maligned when he was in office and continued to malign after his death, who began the practice of singing the Star Spangled Banner at baseball games. This became a practice during the war to instill greater patriotism and love of country during a period of sacrifice.
During World War Two there was a spirit of patriotic unity based on inclusion. There was a task to be performed and by forming a common front and purpose the goal of victory became attainable.
Look what happened following World War Two. The two leaders, one deceased by then, who had been at the helm in the effort to thwart Nazi totalitarianism, Roosevelt and his successor Harry Truman, began to be reviled as disloyal Americans by the same type of intolerable right wing extremists that form today's Tea Party.
Two demagogues joined forces to turn Americans against each other and conquer by division, using the fear of nuclear confrontation amidst a Cold War to insist that conspiracy was afoot in America.
Senator Joseph McCarthy of Wisconsin was a shameless opportunist with strong penchants for power and alcohol, not necessarily in that order. He would stand on the U.S. Senate floor and hold up a piece of paper, insisting that a specified number of Communists were then members of the State Department.
The number continued to change and McCarthy had no answer when alert journalists questioned him about it.
When he ran out of Democrats to malign and President Dwight D. Eisenhower instructed Republicans not to cooperate with his headline hunting McCarthy Committee, he added on the four years of Eisenhower's first administration to the "twenty years of treason" he had earlier attributed to Democrats beginning with FDR's first term in office.