The British soldiers who helped Israel win in '67 - The Jewish Chronicle

In June 1967, Israel crushed Egypt in the Six Day War. However, what is less known was the part played by British mercenaries and Israelis who helped the Royalist forces confront the Egyptian-backed rebels in the civil conflict which ravaged the Yemen from 1962 to 1968. My recent book, The War that Never Was raises the question of how far the covert mercenary campaign during that period contributed to the defeat of Egypt in 1967.

The fighting in the Yemen began with the revolution of September 1962, which was almost certainly provoked, and certainly was supported, by President Nasser. As a large Egyptian expeditionary force sailed down the Red Sea and put into the harbour at Hodeidah, to support the Republican army, the hereditary Ruler, Imam al-Badr, fled from his palace in Sana'a and took refuge in the mountains.

Nasser had grandiose ambitions: he himself had declared that "the road to Tel Aviv lies via the Gulf and Al-Riyadh" - in other words, he planned that the whole Arabian peninsula should become an united Arab republic, which would give him the strength to annihilate his principal enemy, Israel. The British Government's particular worry was that he would over-run their crown colony in Aden – yet when the Imam appealed to them for help, the British were too feeble to answer his request.

Into the breach stepped a handful of former SAS officers determined to retard Nasser's progress. One of them, Lieutenant Colonel Jim Johnson, then working as an underwriter at Lloyds, created a private army of mercenaries, who went out into the Yemeni mountains to train the Royalist forces, set up communications and give the tribesmen basic medical help. From the start, elaborate steps were taken to keep the operation secret and deniable: some members of the Conservative administration were aware of it, but in the House of Commons the Prime Minister, Sir Alec Douglas-Home, claimed that "our policy is one of non-intervention in the affairs of that country". Nor did things change when Labour, under Harold Wilson, came to power in October 1964.

The campaign was financed by Saudi Arabia in whose interest it was to detain and debilitate Nasser's army in the Yemen for as long as possible. Large cheques signed in Jeddah came into Johnson's basement office in Sloane Street, and he allocated the money to the mercenaries' accounts in Jersey. At the same time enormous sums were pouring into the Yemen through Najran in the north and Beihan in the south.

A Boeing Strato-cruiser flew 14 missions into the Yemeni mountains

Much of this wealth went astray, stolen or given away as it travelled by truck or camel train towards the Royalist princes in the mountains. The same was true of incoming arms and ammunition. A more secure means of delivery was needed, and it was the Israelis who provided it - for they, like the Saudis, were eager to keep Nasser distracted elsewhere.

Negotiations were conducted in absolute secrecy, first by the Conservative MP Billy McLean (a close associate of Johnson), who flew privately to Tel Aviv to meet Moshe Dayan, the defence minister, and Meir Amit, head of Mossad. The next envoys were Johnson and his second-in-Command, Tony Boyle, who conferred with Shimon Peres, Director of the Ministry of Defence, and Major General Ezer Weizman, Commander-in-Chief of the Israeli Air Force.

To help preserve security, the mercenaries called Israel "Wales" and Israelis "the Welsh". Later, the operation was known as "Mango", and Israel became "Mango Land". So efficient was the obfuscation that the British Government knew nothing about it. Had word got out, Nasser would have had an immense propaganda coup, and the Saudis would immediately have cut off the supply of gold.

To Israel, it was Operation Leopard, in which a converted Boeing Stratocruiser flew 14 missions into the Yemeni mountains by night, parachuting arms, ammunition and gold directly to the Royalist armies.

The flights were extremely hazardous, for the dropping zones chosen by the mercenaries were among 12,000-foot mountains, and lacked all the navigational aids to which pilots were accustomed. Only small fires and the occasional headlamp purloined from a lorry guided the Stratocruiser in. Major Arieh Oz, pilot on most of the missions, reckons to this day that "for daring, planning and execution, it was a masterpiece of a military operation". His first flight lasted for 14 hours, and he touched down at Tel Nof airforce base, south of Tel Aviv, with only 15 minutes' fuel remaining in his tanks.

The drops undoubtedly did a great deal to bolster Royalist morale, and - though their value cannot be quantified - they certainly increased the difficulties in which the Egyptians found themselves by providing the Imam's followers with rifles, machine guns, explosives, mortar bombs and ammunition. In the course of the civil conflict, Nasser lost 20,000 dead, and came to regard the Yemen as his Vietnam.

The effect on the Six-Day War is equally unquantifiable. There is no doubt that the shattering initial air-strikes in the early morning of 5 June 1967 set Israel on the road to victory; but equally, the fact that 30,000 of Egypt's best troops were still pinned down in the Yemen, and that 20,000 men had been killed there, must have contributed something to the country's defeat. No doubt Israel, with its domination in the air, would have won anyway even if the whole Egyptian army had been present - but the land battle might have been longer and more bloody.

The Israeli high command certainly thought so. Two days after their victory they invited Johnson and Boyle out to Tel Aviv, where they were congratulated by Dayan. They were then flown all over the Sinai battlefield - and they were shocked by the evidence of carnage close beneath them, especially by the sight of wrecked tanks and lesser vehicles packed like lemmings in the Mitla Pass, through which the drivers had vainly tried to escape towards Suez.

In running his private war, Johnson's aim had been to help the Royalists drive Nasser out of the Yemen, and maintain British influence in the Middle East for as long as possible. He had never set out to help Israel. On the contrary: as he saw it, Israel had helped him by flying the para-drop missions. In the end, both sides recognised that they had been of use to each other - and Israel did what Her Majesty's Government had never done, which was to recognise the extraordinary individual effort that Johnson had made.