Meanwhile, in the north of the country, some of the bloodiest fighting since 2001 took place after the LTTE launched massive attacks on Sri Lanka Army defence lines in the Jaffna peninsula on August 11. The LTTE used a force of 400 to 500 fighters in the attacks which consisted of land and amphibious assaults, and also fired a barrage of artillery at government positions, including the key military airbase at Palali. Initially, the Tigers broke through army defense lines around Muhamalai, and advanced further north, but they were halted after 10 hours of fierce fighting. Isolated battles continued over the next few days, but the LTTE was forced to give up its offensive due to heavy casualties.