'If you don't go after the network, you're never going to stop these guys. Never.'

Noting an "Army requirement of 20,000 systems" worth $1.5 billion by 2008, General Dynamics intended to "pursue the Army requirement and displace Syracuse Research," according to a defense industry document. A corporate information campaign would promote Chameleon's virtues to Army and congressional leaders.

"We've pursued business opportunities," a General Dynamics spokesman said last week. "We were well aware of the Army requirement." A spokesman for Syracuse Research declined to comment, citing "contract restrictions."

In Baghdad, confusion only intensified as hundreds and then thousands of new jammers flooded in, some active and others reactive. Duke's shortcomings -- "it was looking like a turkey," the senior Pentagon official said -- grew so grievous by late spring that officials considered scrapping the jammer altogether in favor of Chameleon.

A naval officer, Capt. David J. "Fuzz" Harrison, had spent the winter of 2005-2006 in Baghdad trying to figure out how to fix the jammer problem. "The ground electronic warfare fight that's killing so many soldiers and Marines would be greatly aided by having people here who know electronic warfare," Harrison reported. That meant the Navy, which had extensive experience in electronic combat and had recently been chosen to coordinate all of the military's CREW systems.

Retired Gen. Montgomery C. Meigs, head of the Pentagon's counter-IED effort, returned from Baghdad in early February 2006 with similar conclusions. Expertise was needed in divisions, brigades, regiments and battalions. Harrison and Col. Kevin D. Lutz, commander of Task Force Troy, the counter-IED brigade in Iraq, calculated that nearly 300 electronic warfare officers would be required. The Navy agreed to provide them.

After brief training at Naval Air Station Whidbey Island in Washington state, the first batch of 33 Navy electronic warfare experts -- including submarine, aviation, surface ship and engineer officers and sailors -- arrived in Baghdad on April 15, 2006. Hundreds followed. Distributed throughout the force, they made an immediate impact.

Now soldiers and Marines had an expert to adjust those finicky boxes and antennas, and to offer advice on using jammers as a weapon against radio-controlled bombs. "It was," Meigs later said of the Navy's commitment, "a stroke of genius."

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By the summer of 2006, radio-triggered IEDs had dropped to less than half the total, and they would keep plummeting for the next year. Duke became a valued battlefield asset in Iraq, and 2,300 eventually reached Afghanistan to begin replacing the venerable Acorn, which had first arrived in 2003. The integration of active and reactive jammers in both theaters proceeded apace. "Scar-tissue learning," as Meigs called the process, turned soldiers and Marines into capable electronic warriors.

Yet insurgent bombers found other options. Simple pressure plates -- two metal strips that completed an electrical firing circuit when pressed together by a tire or an unsuspecting boot -- appeared in great numbers. More than one-quarter of bomb triggers were soon classified as "VO": victim-operated.

These included growing numbers of explosively formed penetrators (EFPs), which often used passive infrared triggers tripped by a passing victim. EFPs became as flamboyant as they were deadly; a bomb with 54 warheads configured in nine "arrays" was discovered before detonation on May 17, 2006. Despite increasingly sharp warnings from the Bush administration to Iran, which was accused of supplying the bombs and other war materiel, EFPs continued to take a horrific toll in Shiite-controlled sectors of Iraq.

Six cavalry troopers would be killed in a blast on March 15 of this year, and from April 1 through July 31 roughly 300 EFP attacks occurred. EFPs still account for only about 3 percent of all roadside bombs in Iraq, but the 250 Americans killed by the devices since 2004 amount to 17 percent of all bomb deaths, according to military sources.