The operation began in August of 1940 and although Germany was the overwhelming favorite, things didn't turn out quite as expected. Historian William L. Shirer points out a critical mistake by Hermann Goering in The Rise and Fall of the Third Reich:

We realized that the R.A.F fighter squadrons must be controlled from the ground by some new procedure because we heard commands skillfully and accurately directing Spitfires and Hurricanes on to German formations...For us this radar and fighter control was a surprise and a very bitter one.

On August 12, the Luftwaffe staged a raid on enemy radar stations. Five stations in all were damaged, with one completely disabled. Yet, following a dismal showing in battles on August 15th, Goering called off all future attacks on the radar stations, declaring:

It is doubtful whether there is any point in continuing the attacks on radar stations, since not one of those attacked has so far been put out of action.

German pilots knew that radar granted an advantage to their opponent. German intelligence knew the location of many (if not all) of the radar stations. Shirer believes that this gross miscalculation is one of the major factors why Germany did not win the Battle of Britain. Why was this decision made? Could the available intelligence have allowed them to make a better decision?

Each piece of intelligence has a level of credibility as well as a level of aggregation. A small fragment of data with 100% credibility is worth little. For example: Osama Bin Laden is an Islamic Fundamentalist. Absolutely true but not helpful in stopping specific acts of terror. Aggregate (complete) information with low credibility is also of little use. Advance information regarding an enemy operation with 0% credibility does little good no matter how complete it is.

Usability is a measurement of the value of a piece of information. A simple way to estimate usability would be to multiply the credibility by the level of aggregation. Information that is 50% credible and 50% complete would have a usability of 25%. The fact that the measurements of credibility and aggregation are merely estimates adds additional margin of error to the usability figure.

Hindsight brings tremendous clarity to intelligence because once the events have transpired, it becomes possible to know the true credibility and completeness of the information. It reveals the true connections between distinct fragments of information and filters out the erroneous and misleading debris; the red-herrings.

Goering knew that radar assisted the British, but he did not realize that it cancelled out his numerical superiority. He also incorrectly believed that the German attacks on radar stations were unsuccessful. His decision looks foolish when seen through the lens of hindsight. However, ignoring the truth revealed by history and considering only the information available to Goering, the folly of the decision is not as apparent.

This is the problem I have with the 9/11 Commission. They are looking at intelligence with the benefit of hindsight and blaming the intelligence community and two administrations for missing signals which seem so obvious to the panel. The information reviewed by the panel is the intelligence gathered prior to the 9/11 attacks. In 2004, the credibility and coherence of the information is known; in 2001 it was not. The panel is only reviewing the intelligence which is now known to be relevant to that event. This constitutes but a small fraction of the total intelligence gathered and processed during that time period.

The value in a commission such as this is to improve the way that intelligence is processed. This is done by identifying communication bottlenecks and determining how and where key information slipped through the cracks. However, assigning blame is something to be avoided, unless proven negligence is uncovered. Today, the August 6th PDB provides a vague warning. In the context of August, 2001, it becomes even more benign. The more they concentrate on trivial matters, the less benefit our national security will see from this commission.