Most civil administrations were closed down, the European administrators and civilians evacuating to the south. By mid-December, the Japanese had reached Kroh in the interior of Perak, moving in from Kota Bharu in Kelantan. The Japanese arrived both from the east and by boat along the western coast. Within 16 days of their first landings, they had captured the entire northern part of the Malay Peninsula. The British were left trying to blockade the main road heading south from Ipoh. While the defending troops briefly slowed the Japanese at the Battle of Kampar and at the mouth of the Perak River, the Japanese advance along the trunk road, followed up with bombing and water-borne incursions, forced the British to retreat further south.