Short answers, pulled from the story.
The goal was the capture of Akyab Island, which held a port and all-weather airfield at the tip of the Mayu Peninsula. Fighters and transport aircraft operating from Akyab could cover most of Central Burma at a radius of 250 miles, and medium bombers could reach Rangoon 330 miles away.
Japanese defenders at Donbaik constructed well-concealed, mutually supporting timber-and-earth bunkers that field artillery could not penetrate. A single Japanese company held a front shielded by a tidal creek with nine-foot banks. The attack on the 1st of February 1943 by the Indian 55th Brigade with only eight Valentine tanks failed when tanks became stuck in ditches or were knocked out by Japanese shellfire.
The initial Japanese defense was led by Colonel Kosuke Miyawaki commanding "Miyawaki Force," which consisted of two battalions of the 213th Regiment drawn from the Japanese 33rd Division. The Japanese 55th Division, commanded by Lieutenant General Takeshi Koga, was later dispatched from Central Burma to reinforce the Arakan front.
Brigadier Ronald Cavendish, commander of the British 6th Brigade, was captured along with his adjutant and six staff officers when the Japanese overran his headquarters at the village of Indin on the night of the 5th of April 1943. Cavendish had directed British artillery to fire on Indin just before being overrun; he, some of his staff, and some of their Japanese captors were killed shortly afterwards, almost certainly by that British fire.
British and Indian troops lacked training in jungle warfare, and repeated defeats severely damaged morale. Administration in rear areas in India was poor, roads used as supply routes were inadequate, and reinforcements in some cases had not even completed basic training. The 14th Indian Division headquarters was at one point controlling nine infantry brigades rather than the usual three, far beyond its capacity.
Lieutenant General Noel Irwin attempted to dismiss Lieutenant General Slim from command of XV Corps following the retreat from Arakan. Instead, Irwin was himself relieved of command of Eastern Army and returned to Britain on sick leave. He was replaced by General George Giffard, who focused on rebuilding the army's morale and improving its training.