Public invited to Wednesday events marking fifth anniversary of July 7 Downtown Dallas ambush Public invited to Wednesday events marking fifth anniversary of July 7 Downtown Dallas ambush Families of the fallen officers hope the public continues to remember the sacrifice that law enforcement officers make when they make the pledge to protect and serve. DALLAS - Wednesday marks the fifth anniversary of the July 7 ambush on Dallas police. Families of the fallen officers hope the public continues to remember the sacrifice that law enforcement officers make when they make the pledge to protect and serve. As tensions have continued to intensify between the public and police in the five years since her son's death, Valerie Zamarripa wants people to remember the sacrifice officers make to keep people safe.