on both sides of the Saigon River. He envisioned troops moving into position on one side of the river to form an anvil followed by a rapid move from the other side to hammer the enemy against the anvil. Discussion also turned to the need for extensive clearing to strip the area and deprive the enemy of concealment. By November General Seaman's headquarters was planning not only for Operation Junction City but also for Cedar Falls. Intelligence collection was directed at both operations.

A new approach to assigning intelligence collection responsibilities in III Corps had been taken with the publication of a II Field Force, Vietnam, intelligence collection plan. The plan assigned specific intelligence collection areas, tasks, and responsibilities to U.S. and allied units within the III Corps area; the objective was a closely integrated and coordinated effort by U.S. and allied agencies. Unit collection responsibilities were assigned on the basis of geographic areas. Close liaison was effected between U.S. and allied units from division through battalion level and between U.S. advisers and corresponding commanders of South Vietnamese Army units or province and district chiefs. The plan was designed to provide for the collection of maximum information with minimum duplication of effort.

A step was also taken to improve the intelligence collection effort through the establishment of a source control program in the III Corps area. When fully implemented, this program administratively controlled and identified confidential informants and sources, assisted in their evaluation, prevented utilization of each source by more than one agency and avoided employment of unreliable agents.

Operation Cedar Falls was the first large scale operation to benefit from "pattern activity analysis," a system begun in mid 1966. This procedure consisted of detailed plotting on maps of information on enemy activity obtained from a variety of sources over an extended period of time. As more data were plotted, patterns of activity and locations emerged. It thereby became possible to focus prime attention on those areas of intensive or unusual activity.

Aerial observation and photography, sensors, patrol reports, infrared devices, sampan traffic counts, enemy probes of Regional and Popular Forces posts, agent reports, civilian movement reports, reports of increased antiaircraft fire, disclosures of caches (and the amount and nature of the material in them), and captured documents-these sources and more revealed much about enemy intentions. Increases in road ambushes or bridge destruction