During the Second World War, he led the Australian and British troops at the Siege of Tobruk (1941) and at the Second Battle of El Alamein, achieving decisive victories over Erwin Rommel's Afrika Korps.

When the First World War broke out in August 1914, Morshead resigned his teaching position and his commission in the Cadet Corps to travel to Sydney and enlist as a private in the 2nd Infantry Battalion of the First Australian Imperial Force.

Between the wars Morshead made a successful business career with the Orient Steam Navigation Company, and remained active in the part-time Militia, commanding battalions and brigades.

After his graduation in December 1910, he was awarded a scholarship to complete an education diploma at the University of Melbourne, but decided to defer for a year in order to teach at schools in country Victoria.

[5] While at Melbourne Grammar, he met Myrtle Catherine Woodside, the daughter of a Happy Valley, Victoria, grazier, and the sister of one of Morshead's pupils.

[10] The battalion made the farthest advance of any Australian unit that day, reaching the slopes of Baby 700, but was driven back by a Turkish counter-attack in the afternoon.

[22] His citation, written by his division commander, Major General John Monash, read:This officer has displayed conspicuous ability in administration and organisation of his battalion, which has attained a high standard of fighting efficiency.

[23] Official historian Charles Bean described Morshead as:a dapper little schoolmaster, only 28 years of age, in whom the traditions of the British Army had been bottled from his childhood like tight-corked champagne; the nearest approach to a martinet among all the young Australian colonels, but able to distinguish the valuable from the worthless in the old army practice; insistent on punctiliousness throughout the battalion as in the officers’ mess, with the assistance of a fine adjutant, Lieutenant Jones: and an imperturbable second-in-command, Major White, and with his own experience of fighting as a junior captain of the 2nd Battalion upon Baby 700 in the Anzac Landing, he had turned out a battalion which anyone acquainted with the whole force recognised, even before Messines, as one of the very best.

[28] His citation, written by his new division commander, Major General John Gellibrand, read:For gallantry, initiative and ability in action during the operations on SOMME in August 1918.

On 8 August 1918, during the attack east of Hamel, Lieutenant Colonel Morshead was in command of the special force for the purpose of clearing Accroche Wood.

He executed this task with great skill, and then fought his battalion to its objectives, capturing 500 prisoners, many guns and a large quantity of materiel at very little cost to his own force.

His military ability, fine fighting spirit and cheerfulness under all circumstances had a most inspiring effect upon all ranks and contributed greatly to the success of the operation.

He tried farming, accepting a soldier settlement block of 23,000 acres (9,300 ha) near Quilpie, Queensland, but this venture was a failure, and he returned to Melbourne,[34] where he married Myrtle at Scots Church, on 17 November 1921.

During a visit to England in 1937 as part of his duties with the Orient Line, he had occasion to observe the British Army on manoeuvres in East Anglia, and was impressed by the pace of modern mechanised forces.

[42] The 18th Infantry Brigade finally embarked from Sydney on the Mauretania on 5 May 1940 but en route was diverted to the United Kingdom owing to the dangerous military situation there following the Battle of France.

The Australian force there under Major General Henry Wynter was poorly equipped but the 18th Infantry Brigade was nonetheless given an important role in the defence of Southern England.

[44] Before his other two brigades could arrive from England and Australia, Wynter became seriously ill. Blamey decided to send him home and appointed Morshead to command the 9th Division on 29 January 1941.

[47] The half-trained and half-equipped 9th Division was pitched into the thick of the action almost immediately, steadying the retreat of Commonwealth forces from the newly arrived German Afrika Korps, under General Erwin Rommel, and occupying the vital port of Tobruk.

Morshead was given command of the Tobruk garrison which, as the retreat (known to the Australians as the "Benghazi handicap") continued, became surrounded, hundreds of miles behind enemy lines.

The Axis troops learned to fear the aggressive patrolling of the Australian infantry who dominated no-man's-land and made constant raids on enemy forward positions for intelligence, to take prisoners, to disrupt attack preparations and minelaying operations, even to steal supplies that were not available in Tobruk.

The 9th Division held Tobruk not for eight weeks, but for eight months, during which time three separate relief campaigns by the main Allied force in Egypt failed.

[62] At the Second Battle of El Alamein, the 9th Division was given responsibility for clearing a corridor through the German and Italian forces in the North and threatening to cut off those between the coastal road and the sea.

As the British attack faltered, the main effort switched to the 9th Division, which punched a massive dent into the German and Italian position over the next five days at great cost, "crumbling" the Afrika Korps in the process, and ultimately forcing Rommel to retreat.

During the El Alamein Campaign, the 9th Division suffered 22% of the British Eighth Army's casualties; 1,177 Australians were killed, while 3,629 were wounded, 795 were captured and 193 were missing.

Morshead arrived in Fremantle on 19 February 1943 where he was welcomed home by Lieutenant General Gordon Bennett, who had been his divisional commander in Sydney between the wars.

The Japanese not only held the high ground overlooking the Australian beachhead at Finschhafen, they were rapidly reinforcing their position and were about to mount a major counter-attack.

[74] Vasey soon chafed under Morshead's command, feeling that "he has too many favourites both individually and collectively",[75] with men who had served at El Alamein receiving preferential treatment.

[80] The British government proposed that British Lieutenant General Sir Charles Keightley be given command of a Commonwealth Corps for Operation Coronet, the proposed invasion of Honshu, the main island of Japan, but the Australian government had no intention of concurring with the appointment of an officer with no experience fighting the Japanese, and counter-proposed Morshead for the command.

From 1950 Morshead headed 'The Association', a secret organization similar to the New Guard movement with which he had been involved in the mid-1920s, and which was prepared to oppose communist attempts at subversion.

He did serve as president of the Boy Scouts Association of New South Wales and the Big Brother Movement, a British youth emigration support scheme, and was a trustee of the Gowrie scholarship trust fund,[2] which provided assistance to the descendants of Second World War veterans.