Wikipedia
#OpIsrael is a coordinated cyber-attack by anti-Israel groups and individuals against websites they perceived as Israeli, chiefly through denial of service assaults, database hijacking, database leaks, admin panel takeover, and defacements. Timed for 7 April 2013, the eve of Holocaust Remembrance Day, its stated goal is to "erase Israel from the internet" in protest against claimed crimes committed against the Palestinian people on behalf of Israel. The event is organized and carried out by dozens of factions associated with the Anonymous collective. Websites targeted by the activists included those of banks, schools, non-profit organizations, privately owned small businesses and newspapers in Israel, as well as Israel's national Holocaust museum Yad Vashem and government agencies.
In the leadup to the attack, Israeli organizations made preparations to defend their websites, and cyber-security experts called on home users to increase awareness and take precautions such as changing passwords, not opening strange or suspicious emails, and maintaining especial vigilance when using Facebook. The Israel Internet Association (ISOC) operated a hotline for people to report attacks and published real-time status reports on its website.
Ultimately, #OpIsrael caused no physical damage and was assessed by the Israeli Government's National Cyber Bureau and by some security experts and journalists to have been a failure.