The British Army during the Victorian era served through a period of great technological and social change. Queen Victoria ascended the throne in 1837, and died in 1901. Her long reign was marked by the steady expansion and consolidation of the British Empire, rapid industrialisation and the enactment of liberal reforms by both Liberal and Conservative governments within Britain.

The British Army began the period with few differences from the British Army of the Napoleonic Wars that won at Waterloo. There were three main periods of the Army's development during the era. From the end of the Napoleonic Wars to the mid-1850s, the Duke of Wellington and his successors attempted to maintain its organisation and tactics as they had been in 1815, with only minor changes. In 1854, the Crimean War, and the Indian Rebellion of 1857 highlighted the shortcomings of the Army, but entrenched interests prevented major reforms from taking place. From 1868 to 1881, sweeping changes were made by Liberal governments, giving it the broad structure it retained until 1914.

Upon Victoria's death, the Army was still engaged in the Second Boer War, but other than expedients adopted for that war, it was recognisably the army that would enter the First World War. The Industrial Revolution had changed its weapons, transport and equipment, and social changes such as better education had prompted changes to the terms of service and outlook of many soldiers. Nevertheless, it retained many features inherited from the Duke of Wellington's army, and since its prime function was to maintain an empire which covered almost a quarter of the globe, it differed in many ways from the conscripted armies of continental Europe.

The supreme commander of the British Army was the Commander-in-Chief of the Forces, based in Whitehall. The Commander-in-Chief was primarily responsible for military discipline, training, personnel matters, promotions (which until 1871 were often still obtained through the purchase of commissions) and the transfer of units. He was the Crown's central point of contact for military affairs. Britain had no General Staff until the early twentieth century, and the work of some departments at the War Office was sometimes poorly supervised and inefficient. One of these was the Intelligence department. Although some distinguished soldiers, such as Henry Brackenbury and George Henderson, held the post of Director of Intelligence, they were distracted by questions of organisation and tactical doctrine, in which fields they made their major contributions.

At the beginning of the 19th century, the War Office was a relatively modest government agency responsible for the administration of the British Army, but its organisation was notoriously fragmented and inefficient. Prior to the reforms that followed the Crimean War, the army was administered by a multitude of separate offices and committees, each of which operated with a high degree of autonomy and was often directly accountable to the Crown or various cabinet ministers, leading to overlapping responsibilities and frequent bureaucratic confusion.

The catastrophic logistical and administrative shortcomings that came to light during the Crimean War led to the realisation that the system was outdated and incapable of supporting a modern army. In response, the government initiated a comprehensive administrative reform. In 1855, the office of Secretary of State for War was created, consolidating many of the tasks that had previously been distributed among various ministries. The Secretary of State for War was now responsible to Parliament for the efficiency and administration of the army, but the restructuring was not as comprehensive as it appeared. The Commander-in-Chief retained considerable powers in terms of command, discipline, appointments and promotions, working in parallel with the War Office and reporting to the Secretary of State for War only nominally. The Board of Ordnance was abolished, but many of its functions were simply taken over without being fully integrated into the War Office.

After the Crimean War, thirteen separate military authorities were technically merged into the War Office, but in reality this created a cumbersome and costly bureaucracy with many overlaps and inefficiencies. The Secretary of War and the Commander-in-Chief each ran their own institutions, which maintained separate headquarters – Pall Mall for the War Office and Whitehall for the Commander-in-Chief.

Before the Cardwell reforms in the early 1870s, recruitment for the British Army was largely unregulated and often problematic. Enlistment was usually voluntary, but was encouraged by bounties, which were cash payments to recruits. This system led to widespread abuse, with recruits collecting the bounty, deserting and then repeating the process elsewhere. Recruitment took place in various ways, primarily through regimental recruiting parties, which actively sought out physically fit men in towns and villages, especially in poorer areas. Other recruitment options included pensioners, the regular personnel of militia units and direct recruitment in the individual regimental headquarters. Many recruits were driven to enlist by poverty, unemployment or the prospect of adventure, so that the quality of the new soldiers varied greatly.