"Protesters in Washington Urge Peace with Terrorists"

This phrasing suggests incorrectly that protesters were advocating either inaction with regards to the terrorist attacks on New York and Washington, DC or perhaps even an active negotiation or settlement. The protesters, while having a variety of messages, actually advocated non-violent solutions, or at least ones other than war, and changes in foreign policy that would discourage future terrorist attacks. The headline can be interpreted as suggesting that the protesters were sympathetic to the terrorists. Regardless, the headline is written in a manner that would have led almost all to a strong negative reaction towards the protesters.

"Anti-war rallies in Washington, New York"

This headline provides almost no information other than the general theme and locations of the protests. Consequently, it probably elicited little interest from readers and gave the impression of the protests having little significance.

"Thousands Fill Streets of D.C. to Protest War

This phrase gives some indication of the scale of the protests, not only by stating "thousands," but also by creating an image of filled streets. While the numbers may be generally accurate, the image the headline creates serves to amplify the impression of the size of the protests.

"A Peaceful Justice?"

This headline takes the point of view of the protesters, prompting the reader to consider the possibility that a non-violent response to the terrorist attacks will also bring about justice.