I found this very nice “Freedom Prayer” at National Catholic Register:
Heavenly Father, on this holiday weekend we give thanks to you for the gift and blessing of the freedom we enjoy in our great nation. We praise you, Lord, for inspiring and guiding our founding fathers as they struggled to build our country and create a new way of living with the goal of freedom and justice for all.
We thank you, Lord, for the courageous self-sacrifice and generous spirit of countless people who have given their life’s blood in the defense of freedom and for the pursuit of justice. Keep us faithful to the tradition and example we have inherited; may we leave for the next generation a better world, prepared for the dawning of the Kingdom of Christ, your Son, who lives and reigns with you and the Holy Spirit, one God, forever and ever. Amen.