Honestly ... because I feel that Our Lady has tasked us with this!
In 1917 the Blessed Virgin Mary appeared in Fatima, Portugal and asked us all to pray the rosary everyday for world peace. She also prophesied the 2nd world war, as well as the rise of communism, and the persecution of the Holy Catholic Church. But in the end, she said her Immaculate Heart would triumph, and that there would come to the world an era of peace.
Now I know that this may sound crazy... but I feel that our Lady has tasked us with writing a soundtrack for the triumph of her Immaculate Heart, and specifically, her plan for America, of whom she is the patroness of. In this time period, in the history of the world, I feel that America has a special role in fulfilling God's plan through Our Lady. But, in order for Our Lady's triumph to occur in America, we must first undergo a purification, and all purification requires suffering and sacrifice.
American Vespers is the story of that purification, suffering, and sacrifice, which leads to conversion, and will usher in Our Lady's era of peace.