Squadron Leader Ian McLachlan was Commanding Officer of 3 RAAF Squadron when it sailed to the Middle East in July 1940.

On 15 July 1940, 3 RAAF Squadron embarked on RMS Orontes at Sydney for service overseas.
At this time the unit consisted of the following flying personnel:
Squadron Leader McLachlan (CO).
“A” Flight:
Flight Lieutenant Gordon Steege (OC), Flying Officer Alan Gatward, Flying Officer Alan Boyd, Pilot Officer Peter Turnbull and Pilot Officer Wilfred Arthur.
“B” Flight:
Pilot Officer Charles Gaden (OC), Pilot Officer L. E. Knowles, Pilot Officer V. East, Flying Officer Alan Rawlinson and Flying Officer B. L. Bracegirdle.
“C” Flight:
Squadron Leader P. R. Heath (OC), Flight Lieutenant Blake Pelly, Pilot Officer J. M. Davidson, Flying Officer John Perrin and Pilot Officer M D. Ellerton.
Totally the squadron had 21 officers and 271 of other ranks on 24 July.

The squadron left Australia as an Army Co-op Squadron and just prior to sailing, a number of permanent airmen were posted away and replaced by new personnel. Both Squadron Leaders McLachlan and Peter Heath (who lost his life early in the war) were trained as Army Co-op pilots and not as "fighter pilots" and as Senior Permanent Air Force Officers. Neither did a lot of flying (in fact not too many Permanent Officers did a lot of flying). Consequently neither was fully trained for the Squadron's active Desert Air Force role (i.e. that of a Fighter Squadron).

On 7 August, RMS Orontes arrived at Bombay and the unit was transhipped the same day to HT Dilwara.

HT Dilwara sailed on 11 August and arrived at Suez on 23 August where the squadron disembarked.

In the beginning of its time in North Africa the unit was equipped with one flight of Lysanders, one of Gladiators and one of Gauntlets

On 2 November 1940, squadron headquarters and ground personnel of ‘B’ and ‘C’ Flights of 3 RAAF Squadron moved by road from Helwan to Gerawla. The move started at 08:15 and was completed at 17:15 the next day.
Squadron Leader McLachlan, Flying Officer Alan Gatward, Flying Officer M. D. Ellerton, Flying Officer Alan Boyd, Flight Lieutenant Charles Gaden, Flying Officer B. L. Bracegirdle, Flying Officer Peter Turnbull and Flying Officer Wilfred Arthur moved from Helwan to Gerawla by air on 3 November.
Flight Lieutenant Gordon Steege, Flight Lieutenant Blake Pelly and Flying Officer Alan Rawlinson left their attachments to 208 Squadron and rejoined 3 RAAF Squadron at Gerawla while Flying Officer John Perrin, Flying Officer L. E. Knowles and Flying Officer J. M. Davidson, who also had been attached to 208 Squadron returned to ‘A’ Flight at Helwan.
15 Air gunner/Wireless operators from 3 RAAF Squadron were attached to 208 Squadron.
After the completion of these movements the disposition of the squadron was that at Gerawla there were: Officers: 13 pilots, 1 crew, 6 non-flying and 2 (attached) air intelligence liaison.
Airmen: 185 non-flying, 6 (attached) air intelligence liaison and 1 (attached) Royal Corps Signalist.
Aircraft: 10 Gladiators and 4 Gauntlets (two Gauntlets had been left at 208 Squadron, Qasaba, being unserviceable and awaiting spares).
At Helwan (‘A’ Flight):
Officers: 3 pilots and 1 crew.
Airmen: 5 crews and 32 non-flying.
Aircraft: 6 Lysanders and 2 Gladiators (in reserve for ‘B’ and ‘C’ Flights).
Attached to 208 Squadron:
Officers: 2 crew.
Airmen: 5 crew and 15 non-flying.
Attached to 6 Squadron:
Airmen: 6 crew and 14 non-flying.
At Hospital:
2 airmen.
At Abu Sueir (on anti-gas course):
2 airmen.

Between 15:30 and 15:45 on 10 December, a formation from the whole 151^o Gruppo took off from A3 to escort Ba.65s in the Bir Enba – Sidi Barrani area. The 366^a and 367^a Squadriglie flew direct cover of the assault aircraft while the 368^a Squadriglia acted as top cover.
Pilots from 366^a Squadriglia were Capitano Bernardino Serafini, Tenente Guglielmo Chiarini, Sottotenente Amedeo Guidi, Sottotenente Carlo Albertini, Sergente Maggiore Cesare Chiarmetta, Sergente Maggiore Fiorenzo Milella and Sergente Antonio Camerini. Pilots from the 368^a Squadriglia were Capitano Bruno Locatelli, Sergente Maggiore Davide Colauzzi, Tenente Orfeo Paroli (aborted due to mechanical problems), Sergente Ottorino Ambrosi, Tenente Giuseppe Zuffi, Sergente Mario Turchi and Sottotenente Furio Lauri together with Maresciallo Giulio Cesare of the 366^a Squadriglia. Not all the participating pilots from the 367^a Squadriglia are known but included were Capitano Irzio Bozzolan, Sergente Maggiore Rodolfo Benco, Sergente Maggiore Gino Bogoni, Sergente Tolmino Zanarini, (plus possibly other three pilots).
After the attack of the Bredas, the close escort Squadriglie went down to strafe. The 366^a Squadriglia did five passes and then it was the turn of the 367^a Squadriglia. The weather in the meantime was again deteriorating and was not possible to maintain visual contact between the two covering Squadriglie and the strafing one.
Because of this, the 367^a Squadriglia was surprised from astern by a formation of Glosters while intent in strafing. After a short combat the CR.42s were able to disengage, claiming only a probable victory by an unknown pilot but losing Sergente Bogoni’s CR.42 and getting Sergente Maggiore Benco’s (wounded in the right foot) and Sergente Zanarini’s fighters damaged. Capitano Bozzolan had a narrow escape when pursued by two Gladiators that damaged his engine; he was forced to land in the midst of the enemy armoured cars with a stopped engine. Suddenly the Fiat A74 engine restarted and Bozzolan was able to do a touch-an-go, just managing to return to A3.
They had run into Gladiators from 3 RAAF Squadron. Five Gladiators piloted by Squadron Leader McLachlan, Flight Lieutenant Gordon Steege, Flying Officer Alan Gatward, Flying Officer B. L. Bracegirdle and a fight unknown pilot (the ORB only names four pilots but all combat reports states five Gladiators) had taken off from ALG 74 at 15:40 to carry out an offensive patrol over Tummar. They reported encountering twelve CR.42s that were ground strafing Allied troops near Tummar West. The Gladiators attacked the enemy aircraft and in the ensuing battle, Squadron Leader McLachlan shot one down which he saw strike the ground whilst Flight Lieutenant Steege and Flying Officer Gatward each got a possible. These were later confirmed. All Gladiators returned to base at 17:10. According to some sources Steege and Flying Officer Gatward each claimed 1 and 1 probable CR.42 in this combat, but this can’t be verified with 3 RAAF Squadron’s Operations Record Book nor the combat reports.
Flight Lieutenant Steege reported:

”5 Gladiators led by me were flying at 2000 ft [600 meters] on an Westerly Course about 2 Miles [3.2 kilometres] ENE of NEBEIWA at 1645 when Aircraft were observed Dive Bombing The road running N – South beside the West Edge of West Tummar.
E.A. were carrying an orthodox D. B. from about 3000 ft [900 meters].
Own formation climbed into sun. During this, one E.A. climbing from an attack evidently saw our formation as he continued to climb S.E. I climbed after him and saw my incendiaries passing around him. He stalled to the right as I did, about 500 feet [150 meters] below him.
The remained of own formation were then also engaging E.A.
I followed another from astern at 4000 ft [1,200 meters] and got in several good bursts. He was climbing slowly and appeared to attempt to turn into a head on attack. I fired a long burst into him from about 150 yds [140 meters] and he went into a steep spiral dive 3 turns of which I counted. I then lost sight of him.
During the engagement 5 S 79s were seen to pass above W. Tummar on a West Course at about 7000 ft [2,100 meters] but it was not practical to chase them.”

”When diving from [unreadable] towards E.A. I saw one E.A. proceeding WEST low down on my starboard. I dived on him from the beam and followed him round until almost directly astern & slightly above. I opened fire at a range of approx 50 yds [45 meters] and after a short burst E A which was flying straight at about 200 ft [60 meters] slewed right and dived into the ground. I saw E.A. strike the ground in a cloud of dust and then turned away to avoid another E.A. I had not seen E.A. burning. I returned EAST to [incomprehensible].”

”Own formation attacked out of sun and appeared to be observed by two E.A. only.
I arrived over the area to find three E.A. in echelon about 500 ft [150 meters] below me, apparently preparing for another dive bombing attack on target.
By half rolling and diving I came astern the last aircraft at about 150 yards [137 meters] where I opened fire. The aircraft when fired on commenced a very steep climbing turn from which it spun away. I was unable to observe the result of this spin as by this time I was in the middle of a fight and was taking avoiding action. I followed another aircraft out to the NORTH but was quickly outdistanced by his superior speed. I returned to the scene of the fight but the E.A. had gone home and our formation formed up again.”

On 27 January 1941, many pilots of 3 RAAF Squadron were promoted. Squadron Leader McLachlan was promoted to temporary Wing Commander, Flight Lieutenant D. Campbell and Flight Lieutenant P. Jeffrey was promoted to temporary Squadron Leaders while Flying Officers John Perrin and Alan Rawlinson was promoted to temporary Flight Commanders.

On 31 January 1941, Wing Commander McLachlan of 3 RAAF Squadron was awarded the DFC for “determined leadership, zeal and devotion to duty”. The same decoration was also awarded to Flying Officer Ernest Mason of 274 Squadron for “Initiative, courage and devotion to duty”.

On 13 February, Wing Commander McLachlan was appointed OC RAF Station Benina and Squadron Leader P. Jeffrey was appointed to temporary CO of 3 RAAF Squadron.

McLachlan ended the war with 1 biplane victory, this one being claimed while flying Gloster Gladiators.

Claims:

Kill no.	Date	Time	Number	Type	Result	Plane type	Serial no.	Locality	Unit
	1940
1	10/12/40	15:40-17:10	1	CR.42 (a)	Destroyed	Gladiator		near Tummar West	3 RAAF Squadron

Biplane victories: 1 destroyed.
TOTAL: 1 destroyed.
(a) Claimed in combat with the 367^a Squadriglia, 151^o Gruppo, which lost 1 aircraft and got 3 damaged while claiming 1 probable. 3 RAAF Squadron claimed 1 and 2 probables without losses.

Sources:
3 RAAF Squadron Association
Desert Prelude: Early clashes June-November 1940 - Håkan Gustavsson and Ludovico Slongo, 2010 MMP books, ISBN 978-83-89450-52-4
Fighters over the Desert - Christopher Shores and Hans Ring, 1969 Neville Spearman Limited, London
Gloster Gladiator Home Page - Alexander Crawford.
National Archives of Australia
Those Other Eagles – Christopher Shores, 2004 Grub Street, London, ISBN 1-904010-88-1
Additional information kindly provided by Ludovico Slongo.