Somalia’s violent Islamist movement has been driven out of its headquarters in the southern port city of Kismayo.
It was the first amphibious assault by African troops since independence in the 1960s.
A Kenyan task force bombarded Kismayo then landed troops from seven ships, locals said. They then battled the al Shabab which rushed troops to the city’s port and its beaches three miles to the north.
Joined by Somali government troops, the Kenyans squeezed al Shabab from the north and with an attack from the south - which had followed months of painstaking operations - Kenyan forces inched forward against the Islamists, who claim allegiance to al Qaeda.
Kenyan military spokesman Colonel Cyrus Oguna said: "We came from the beach side and we're moving towards the main city. Our surveillance aircraft are monitoring every event taking place on the ground.
"For now, we're not everywhere. We've taken a large part of it without resistance. I don't see anything major happening," he added.
Kismayo is the most important strategic asset held by al Shabab. It has been the centre of its economic operations since it was driven from Mogadishu a year ago.
The natural port has been a money spinner by exporting charcoal and importing diesel which is then smuggled throughout east Africa. It has also been the only route for the importation of weapons by the radical Islamist group.
Samantha Lewthwaite, 28, the British wife of 7/7 bomber Jermain Lindsay, is believed to have fled to Kismayo after she was allegedly involved in a bomb plot in Kenya’s second city, Mombasa.
Kenyan police issued an arrest warrant for the mother of three soon after they uncovered the alleged plot last December.
Al Shabab had its roots in the Islamic Courts Union government which was established in Mogadishu after almost two decades of chaos and mayhem caused by warlords in Somalia.
The courts fell foul of the US which encouraged Ethiopia to drive it from power in 2007.
Extremists in the movement formed al Shabab and began reaching out to terrorist organisations around the world for support while conservative members of the courts eventually joined the transitional government. Its troops have joined the battle for Kismayo.
British staff officers have been involved in the planning of African Union operations alongside the Somali government in Mogadishu.
Their deployment to the region follows widespread concern that al Shabab had established al Qaeda-style training camps for Somalis based in the west, especially in the UK.
About 200 foreign fighters, of whom 50 are believed to be British, are reported to have joined al Shabab, western intelligence agencies have said.
