That September day, we came together as a nation. The test before us is to sustain that unity of purpose and meet the challenges now confronting us. We need to design a balanced strategy for the long haul, to attack terrorists and prevent their ranks from swelling while at the same time protecting our country against future attacks. We have been forced to think about the way our government is organized. The massive departments and agencies that prevailed in the great struggles of the twentieth century must work together in new ways, so that all the instruments of national power can be combined. Congress needs dramatic change as well to strengthen oversight and focus accountability.

As we complete our final report, we want to begin by thanking our fellow Commissioners, whose dedication to this task has been profound. We have reasoned together over every page, and the report has benefited from this remarkable dialogue. We want to express our considerable respect for the intellect and judgment of our colleagues, as well as our great affection for them. We want to thank the Commission staff. The dedicated professional staff, headed by Philip Zelikow, has contributed innumerable hours to the completion of this report, setting aside other important endeavors to take on this  all-consuming assignment. They have conducted the exacting investigative work upon which the Commission has built. They have given good advice, and faithfully carried out our guidance. They have been superb. We thank the Congress and the President. Executive branch agencies have searched records and produced a multitude of documents for us. We thank officials, past and present, who were generous with their time and provided us with insight. The PENTTBOM team at the FBI, the Director’s Review Group at the CIA, and Inspectors General at the Department of Justice and the CIA provided great assistance. We owe a huge debt to their investigative labors, painstaking attention to detail, and readiness to share what they have learned. We have built on the work of several previous Commissions, and we thank the Congressional Joint Inquiry, whose fine work helped us get started. We thank the City of New York for assistance with documents and witnesses, and the Government Printing Office and W.W. Norton & Company for helping to get this report to the broad public. We conclude this list of thanks by coming full circle: We thank the families of 9/11, whose persistence and dedication helped create the Commission. They have been with us each step of the way, as partners and witnesses. They know better than any of us the importance of the work we have undertaken. We want to note what we have done, and not done. We have endeavored to provide the most complete account we can of the events of September 11, what happened and why.