The 'Battle of Kota Bharu' was fought between Japanese and British-led commonwealth and imperial forces in the north-eastern corner of Malaya (8 December 1941).

The battle started just after 00.00 on 8 December 1941 (local time), before the Japanese 'Ai' carrierborne attack on Pearl Harbor, and as such was the first significant battle of the Pacific War.

Kota Bharu, the capital of Kelantan state on the north-eastern coast of Malaya, was at the time the base of operations in northern Malaya for the warplanes of the Royal Air Force and Royal Australian Air Force: there was a runway at Kota Bharu and two more at nearby Gong Kedak and Machang. In the battle, the Japanese losses were significant because of sporadic Australian air attacks, Indian coastal defences and artillery fire.

The Japanese invasion plan involved landing troops of Lieutenant General Takuro Matsui’s 5^th Division at Pattani and Songkhla on Thailand’s south-eastern coast, and troops of Lieutenant General Renya Mutaguchi’s 18^th Division, both elements of Lieutenant General Tomoyuki Yamashita’s 25^th Army, at Kota Bharu on Malaya’s north-eastern coast. The forces landed in Thailand were to drive across to the western coast and invade Malaya southward through the north-western state of Kedah, while those landed in Malaya were to advance southward down the eastern coast from Kota Bharu and into the interior of Malaya.

The British plan for defending against an attack from Thailand into north-western Malaya was the 'Krohcol' pre-emptive attack into southern Thailand to take strategically vital positions and delay any offensive. The British plan for the defence of Malaya’s eastern coast took the form of fixed beach defences by Major General A. E. Barstow’s Indian 9^th Division along the northern stretch of the coast and two-thirds of Major General H. Gordon Bennett’s Australian 8^th Division defending the southern stretch of the coast. (The remaining one-third of the Australian division was deployed to Ambon, West Timor and Rabaul.)

The Japanese attack was entrusted to Yamashita’s 25^th Army. The relevant forces departed the harbour of Samah on Hainan island on 4 December 1941, and additional transport vessels carrying more troops joined the convoy from Saigon in the southern Vietnam area of Vichy French Indo-China. A Lockheed Hudson twin-engined reconnaissance aeroplane of the RAAF discovered the Japanese convoy, and Admiral Sir Tom Phillips, the British naval commander in the Far East, ordered the battle-cruiser Repulse to cancel its planned trip to Darwin in northern Australia and return to Singapore as quickly as possible. The invasion force was spotted again on 7 December by a Consolidated Catalina twin-engined flying boat of No. 205 Squadron RAF, but the 'boat was shot down by five Nakajima Ki-27 single-engined fighters before it could radio its report to air headquarters in Singapore: the eight men on board the Catalina were thus the first Allied casualties of the war with Japan.

Before their 'E' (ii) invasion, the Japanese had recruited a small number of disaffected Malays into a fifth column organisation called the 'Tortoise Society'. The Malayan police were aware of the society’s existence and had arrested a number of its leaders just before the Japanese landings, but at Kota Bharu members of the society were still at large and could thus provide assistance to the invading force, for which they acted as guides.

Air Marshal Sir Robert Brooke-Popham, commanding officer of the British Forces in the Far East, fearing that the Japanese fleet was trying to provoke a British attack and thus provide an excuse to go to war, hesitated to launch 'Matador', the British plan to destroy the invasion force before or during the landing, on 7 December, and thus opted to delay the operation’s start at least for the night. Shortly after 00.00 on 7/8 December, Indian soldiers patrolling the beaches at Kota Bharu spotted three large shadows: these were the transport vessels Awazisan Maru, Ayatosan Maru and Sakura Maru, which were dropping anchor about 1.85 miles (3 km) off the coast. The ships were carrying approximately 5,200 troops of the 'Takumi' Detachment, which was commanded by Major General Hiroshi Takumi on board Awazisan Maru. Most of these troops were veterans of the war in China.

The Japanese invasion force comprised units of the 18^th Division. These units were the 56^th Regiment, commanded by Colonel Yoshio Nasu on board Sakura Maru, supported by one mountain artillery battery of the 18^th Mountain Artillery Regiment commanded by Lieutenant Colonel Katsutoshi Takasu, the 12^th Engineer Regiment commanded by Lieutenant Colonel Ichie Fujii, the 18^th Division Signal Unit, one company of the 12^th Transport Regiment, one company of the 18^th Division Medical Unit, and No. 2 Field Hospital of the 18^th Division Medical Unit. The naval escort was provided by the Kota Bharu Invasion Force under the command of Rear Admiral Shintaro Hashimoto and comprising the light cruiser Sendai, the destroyers Ayanami, Isonami, Shikinami and Uranami, the minesweepers W-2 and W-3, and the submarine chaser Ch-9.

The invasion began with a bombardment at around 00.30 local time on 8 December: at this moment the Japanese carrierborne warplanes flying toward Pearl Harbor were about 50 minutes away from their destination. The loading of landing craft had started almost as soon as the transport vessels had dropped anchor. Rough sea and strong wind hampered the operation and a number of smaller craft capsized, several Japanese soldiers being drowned. Despite these difficulties, by 00.45 the first wave of landing craft was heading for the beach in four lines.

The defending infantry were men of Brigadier B. W. Key’s Indian 8^th Brigade of Barstow’s Indian 9^th Division, supported by four 3.7-in (94-mm) mountain howitzers of Major J. B. Soper’s 21^st Mountain Battery. The 3/17^th Dogra Regiment, under the command of Lieutenant Colonel G. A. Preston, was responsible for the 10-mile (16-km) stretch of coast which was the Japanese force’s selected landing site. The Indians had fortified the narrow beaches and islands with landmines, barbed wire and pillboxes, and were supported by the 73^rd Field Battery of the 5^th Field Regiment, Royal Artillery, deployed adjacent to the nearby airfield. The area defended by the 3/17^th Dogras consisted of the narrow beaches of Badang and Sabak at Kota Bharu: these beaches were split by the two estuaries through which the Pengkalan Chepa river debouched through a maze of creeks, lagoons and swampy islands, behind which was the Kota Bharu airfield and the main road inland.

The Dogras immediately opened intense fire on the invasion force with artillery and machine guns. By 00.00, the first waves of Japanese troops were heading toward the beach front in landing craft. The first and second waves of Japanese troops were initially pinned on the beach by the intense fire from the Dogras' pillboxes and trenches, but after vicious hand-to-hand fighting made a breach in the defences on the estuary’s southern bank. On the northern bank the Japanese were pinned on an island, where dawn found them trapped in the open. Allied aircraft from the nearby airfields began attacking both the invasion shipping and the soldiers trapped on the island. Japanese casualties in the first and second waves were heavy. The Japanese managed to get off the beach only after the two pillbox positions and supporting trenches had been destroyed. Despite their heavy resistance, the Dogras were forced to retreat to their defences in front of the airfield. Key brought forward his reserves, the 2/12^th Frontier Force Regiment and the 1/13^th Frontier Force Rifles, to support the Dogras. At 10.30, Key ordered an attempt to retake the lost beaches with the 2/12^th Frontier Force Regiment attacking from the south and the 1/13^th Frontier Force Rifles attacking from the north. The fighting on the beaches was heavy with both sides suffering more casualties. The British forces made some progress but were unable to close the breach. In the afternoon, a second attack went in but failed again to close the breach.

The airfield at Kota Bharu had been evacuated, and by dusk on 8 December, in conditions of very low visibility, the Japanese were now able to infiltrate between the British units and, given the possibility of Japanese landings farther to the south, Key asked for permission from Barstow and Lieutenant General Sir Lewis Heath. commander of the Indian III Corps, to withdraw should this become necessary.

The RAAF’s No. 1 Squadron, based at RAF Kota Bharu, launched 10 Hudson light bombers, each carrying four 250-lb (113-kg) bombs, to attack the Japanese transport vessels. In the total of 17 sorties flown, the squadron lost two Hudson aircraft shot down and three badly damaged. One Hudson, flown by Flight Lieutenant John Graham Leighton Jones, crashed into a fully laden landing craft after being hit while strafing the beach-head, killing some 60 Japanese soldiers on board. Only five Hudson bombers remained airworthy at the end of the battle.

All three of the Japanese troopships were significantly damaged, but while the 9,788-ton Ayatosan Maru and 7,146-ton Sakura Maru were still able to sail, the 9,794-ton Awazisan Maru was left burning and was abandoned, the attacks by No. 1 Squadron having killed or wounded at least 110 of her crew. The wreck later sank on its own or was torpedoed by the Dutch submarine K-XII on 12 December.

Despite the strength of the defence, Takumi now had three full battalions of infantry ashore by the middle of the morning of 8 December. Counterattacks launched by Key failed and the Japanese took Kota Bharu town on 9 December. After fierce fighting during the night, threatening the airfield, Lieutenant Colonel A. E. Cumming’s 2/12^th Frontier Force Regiment attempted to hold the airfield and put up a brilliant rearguard action. Key asked for and was now given permission to withdraw from Kota Bharu.

The Japanese claim that the landings at Kota Bharu were some of the most violent of the whole 'Campaign for Malaya': it is estimated that they suffered an estimated 300 men killed and 500 wounded.