The Hadfield-Spears Ambulance Unit was an Anglo-French volunteer medical unit which served initially with the 4th French army in Lorraine, eastern France, during the Second World War from February 1940 until it was forced to retreat on 9 June ahead of the German advance. Its official French designation at that time was Ambulance Chirurgical Légère de Corps d’Armée 282. The unit made its way across France via Bordeaux to Arcachon from where it was evacuated back to Britain, arriving at Plymouth on 26 June. The unit re-grouped and re-equipped in Britain before sailing on 20 March 1941 for the Middle East, landing at Suez on 2 May. Under the designation of HCM (Hôpital chirurgical mobile) 3 Ambulance Hadfield-Spears, it was attached to the Free French forces (1st Free French Division) in the Middle East, North Africa, Italy and France before being dissolved in Paris in June 1945 on the order of General Charles de Gaulle.
The unit was established during the Phoney War with £100,000 donated by Sir Robert Hadfield, the British steel tycoon. He had entrusted the money to his wife, Lady Frances Belt Hadfield, asking that she find a suitable good cause. Lady Hadfield, a francophile like her husband, spent most of the year at their villa at Cap Ferrat in the south of France. She explained to the French Consulate in London that 'the gift was the repayment of a debt she owed to France for the happiest years of her life'. In the First World War, this well-connected American from Philadelphia had been one of the first to start a Red Cross hospital for the treatment of wounded and sick servicemen. This hospital at Wimereux, near Boulogne-sur-Mer, was run entirely at her own expense. Lady Hadfield, CBE, died in London on 6 November 1949.
At the start of the Second World War, Lady Hadfield was 77 and no longer able to run a field hospital. Accordingly she turned to another American – her friend, the novelist Mary Borden, who was known to her friends and family as 'May'. The latter had, at her own expense, also set up a hospital for the French army in July 1915 (l'Hôpital Chirugical Mobile No 1); now she wanted to help during the new conflict. Mary had close ties with France – it was while her unit was on the Somme in 1916 that she met Captain Edward Louis Spears, a British liaison officer attached to the French army. He was subsequently promoted to a General Staff Officer 1st Grade, liaising between the French Ministry of War and the War Office in London. They were married in 1918 and living in Paris at the end of the war. Spears later became a Member of Parliament; his pro-French views in the Commons earning him the nickname of 'the Member for Paris'. They had a wide circle of influential friends, both British and French, whom they entertained at their London home during the inter-war period. Mary Borden (Mrs Spears) agreed to be in charge of the (largely British) female personnel – the nurses and drivers of Lady Hadfield's new field hospital with its 100 beds. Mary Spears was generally known as 'Madame la Générale' by the French – a reference to her husband's rank in the British army. The French military 'Service de Santé' agreed to provide the male staff for the medical unit, including doctors, orderlies and drivers for the unit's heavy trucks.