Major-General Sir Edward Louis Spears, 1st Baronet, KBE, CB, MC (7 August 1886 – 27 January 1974) was a British Army officer and politician. He served as a liaison officer between British and French forces during both World Wars. From 1917 to 1920, he was head of the British Military Mission in Paris, concluding the First World War as a brigadier-general. Between the wars, he was a Member of the House of Commons of the United Kingdom. During the Second World War, he resumed his role as an Anglo-French liaison officer, holding the rank of major-general.

Spears was born on 7 August 1886 at 7 Chaussée de la Muette in the Passy district of Paris. His parents, Charles McCarthy Spiers and Melicent Marguerite Lucy Hack, were British residents of France. His paternal grandfather, Alexander Spiers, was a lexicographer known for publishing an English-French and French-English dictionary in 1846, which was widely used in French colleges.

During his childhood, his parents separated, and his maternal grandmother played a significant role in his upbringing. He moved frequently with his grandmother, including to Menton, Aix-les-Bains, Switzerland, Brittany, and Ireland. As an infant, he contracted diphtheria and typhoid and was considered physically delicate. However, after two years at a boarding school in Germany, his health improved, and he became a strong swimmer and athlete. His friends referred to him by the name Louis.

In 1918, Spears changed the spelling of his surname from Spiers to Spears. He stated that this change was due to frequent mispronunciations of his original name, though it has been suggested that he sought a name that appeared more English, particularly given his rank as a brigadier-general and his position as head of the British Military Mission to the French War Office. He denied having Jewish ancestry, but his great-grandfather, Isaac Spiers of Gosport, was married to Hannah Moses, a shopkeeper from the same town. His ancestry was known at the time; in 1918, the French ambassador in London referred to him as "a very able and intriguing Jew who insinuates himself everywhere".

In 1903, Spears joined the Kildare Militia, the 3rd Battalion of the Royal Dublin Fusiliers. He acquired the nickname "Monsieur Beaucaire", a reference to the protagonist of a novel by the same name. The nickname remained with him, used by both of his wives, with his first wife often shortening it to "B."

In 1906, he was commissioned into the regular army with the 8th Royal Irish Hussars. That same year, he published a translation of Lessons of the Russo-Japanese War, a book by a French general. His upbringing, which involved instruction from a series of tutors, had not prepared him for socializing in military circles, and he struggled to adapt to life in the officers' mess. He was known to be tactless and argumentative, often positioning himself as an outsider—something that characterized much of his life.

In 1911, Spears worked at the War Office on the development of a joint Anglo-French codebook. He continued his interest in military translations, publishing Cavalry Tactical Schemes, another translated French military text, in 1914. In May of that year, he was sent to Paris to work at the French Ministry of War, tasked with establishing contact with British agents in Belgium.

With the outbreak of World War I in August 1914, Spears left Paris for the front on the orders of his colonel at the War Office. He later claimed that he was the first British officer to reach the front lines.