In Gaza Conflict, Fighting With Weapons and Postings on Twitter You furnish the pictures, the American press baron boasted a century ago, as the story goes, and I'll furnish the war. The violent conflict in Gaza between Hamas and Israel, halted after a cease-fire agreed to on Wednesday, has certainly produced powerful images of death and suffering that have been immediately circulated through social networks, no newspaper baron needed. The Israel Defense Forces, which concluded that it had failed to explain its actions adequately during the last Gaza war, in late 2008, had extensive plans to do a better job this time, according to news accounts in Israel. The power of social networking - as musicians, journalists and businesses have quickly learned - is that when done right, the audience does the work, passing on the message to others, who in turn pass it on. But it is a tricky business, mixing the gravity of war with a medium that can appear obsessed with triviality. In fact, early on, Israel was criticized for a program on the military's blog - something that began months before the Gaza conflict - that gives "badges" to visitors for their contributions to the cause on social networks. One critic accused Israel of the "gamification" of war. Certainly, when you engage social networks, you lose control of your message, for example, once a Twitter posting has flown. And indeed, the Israeli military has gotten off to an uneven start. Barely hours after Israel had killed the head of Hamas's military wing, Ahmed al-Jabari, leading to Hamas's firing missiles into Israel, the official Israeli military Twitter feed, now with 200,000 followers, circulated posters that showed missiles falling toward the Eiffel Tower, the Statue of Liberty and the Sydney Opera House, asking, "What would you do?" Below was the note: "Share this if you agree that Israel has the right to self-defense." But that "soft" message was accompanied with more aggressive online behavior that was immediately criticized as off key. The military posted a video to YouTube showing the Jabari assassination, which YouTube briefly took down but then returned, saying the removal was in error. There also was a poster of Mr. Jabari, shaded blood-red with the word "Eliminated" stamped on it, and a taunting Twitter posting from the military: "We recommend that no Hamas operatives, whether low level or senior leaders, show their faces above ground in the days ahead." That posting earned a reply from the military wing of Hamas, Alqassam Brigades, addressed to the Israeli military's Twitter handle, @IDFspokesperson, "Our blessed hands will reach your leaders and soldiers wherever they are (You Opened Hell Gates on Yourselves)." The dialogue between the English-language Twitter feeds of the two combat enemies that day ended there. To journalists who have tracked the Israeli military's immersion into social networking during the Gaza conflict, the boastful language has given way to postings that focus on the suffering within Israel. The shift makes sense, they say, because the material celebrating success by the military will not speak beyond the country's supporters. Gilad Lotan, a data scientist who studies how information spreads in social networks, said that Israel had succeeded in getting its message out. "The I.D.F."s "propaganda" has given Israel supporters all over the world digital ammunition that they can use to share, decontextualize and tell their version of the Israeli struggle," he wrote in an e-mail from Israel, where he was visiting. And it has worked. These pieces of media have been shared immensely on Twitter, Facebook, Instagram and Tumblr. To Ali Abunimah of the Chicago-based, pro-Palestinian Web site Electronic Intifada, to look at the online "branding" by either side is to look away from the reality on the ground. "You can put in years of effort, and spend a lot of money," he said, "and make tremendous efforts to control the narrative, but the reality - when the missile hits and flattens a house - that's what changes the narrative." Throughout the conflict, the use of social media has made it easier for each side to cocoon itself. There are rival Twitter hashtags: #pillarofdefense for the Israeli side, #gazaunderattack for the Hamas side. Sometimes the same events get replayed on each Twitter feed with radically different meanings. Bombs fired from Gaza that land near Jerusalem are hailed by Alqassam as showing the ability of its forces to take the fight to the enemy, while the Israeli military feed includes the news as an example of wanton destruction. In a rare case of cross-pollination, on Tuesday, Alqassam, which has 40,000 followers on Twitter, forwarded a post from the Israeli military that reported that five soldiers had been wounded by a missile fired from Gaza. This week, the efforts to shape perceptions of the conflict have gone all the way to the top of the Israeli government. On Monday evening, Prime Minister Benjamin Netanyahu posted to his 120,000 Twitter followers an acknowledgment of the country's efforts in social networking: "I would like to thank all the citizens of Israel and all over the world who are taking part in the national information effort." Twitter being Twitter, just below that comment appeared the reply: ."@netanyahu "national information effort" is really hard to put in 140 characters. can we just use propaganda from now on?" Shortly after his thank you, Mr. Netanyahu posted for a second time a photograph from the week before of an Israeli baby (face obscured) who had been injured by missiles fired from Gaza, with the caption, "For Hamas, every time there are civilian casualties, that's an operational success." Roughly the same time Mr. Netanyahu first posted the photo of the injured baby, Alqassam Brigades used Twitter to share photos of an infant killed by an Israeli strike. Each had appended a comment - Mr. Netanyahu ("I saw today a picture of a bleeding Israeli baby. Hamas deliberately targets our children.") and Alqassam ("Where is the media coverage of Israel's crimes in Gaza?"). Robert Mackey contributed reporting.