The British mobilize 450,000 troops to defeat the 80,000 troops of the main Boer armies in early 1900.

Transvaal President Paul Kruger travels to Europe in an unsuccessful attempt to enlist foreign suport.

Farmer-soldier Louis Botha commands the Transvaal force as commandant general; jurist James Barry Hertzog leads an Orange Free State army.

The British occupy Pretoria, the Transvaal’s capital.

The Orange Free State, annexed by the British in 1900, is renamed the Orange River Colony.

Later in the year, German-armed Afrikaaner farmer commandos initiate a guerilla war against the British.

The Boers around beseiged Ladysmith are also growing weak from lack of forage.

With little action, many fighters take unauthorized leave or bring their families into the siege encampments.

Eventually, with the Tugela in flood, preventing Buller from giving any support, some younger leaders persuade General Piet Joubert to order a storming attempt on the night of January 5, 1900, before another relief attempt can be made.

The British line south of Ladysmith runs along a ridge known as the Platrand.

The occupying British troops have named its features Wagon Hill to the west and to the east Caesar's Camp.

Under Ian Hamilton, they have constructed a line of forts, sangars and entrenchments on the reverse slope of the Platrand.

In the early hours of January 6, 1900, Boer storming parties under General C.J. de Villiers begin climbing Wagon Hill and Caesar's Camp.

They are spotted and engaged by British working parties who are emplacing some guns.

The Boers capture the edge of both features, but cannot advance further.

British counter-attacks also fail.

At noon, de Villiers makes another attack on Wagon Hill.

Some exhausted defenders panic and flee, but Hamilton leads reserves to the spot and recaptures some empty gun pits.

Late in the afternoon, a terrific rainstorm breaks, and the Boers withdraw under cover of it. 

The British suffer one hundred and seventy-five killed and two hundred and forty-nine wounded.

Fifty-two dead Boers are left in the British positions, but their total casualties are not recorded.

Boer troops defeat the British Army at the Battle of Spion Kop on January 24.

The British government, with the sieges still continuing is compelled to send two more divisions plus large numbers of colonial volunteers.

By January 1900 this had become the largest force Britain had ever sent overseas, amounting to some 180,000 men with further reinforcements being sought.

While watching for these reinforcements, Buller makes another bid to relieve Ladysmith by crossing the Tugela west of Colenso.

Buller's subordinate, Major General Charles Warren, successfully crosses the river, but is now faced with a fresh defensive position centered on a prominent hill known as Spion Kop.

In the resulting battle, British troops capture the summit by surprise during the early hours of January 24, but as the early morning fog lifted they realize too late that they are overlooked by Boer gun emplacements on the surrounding hills.

The rest of the day results in a disaster caused by poor communication between Buller and his commanders.

Between them they issue contradictory orders, on the one hand ordering men off the hill, while other officers order fresh reinforcements to defend it.

The result is three hundred and fifty men killed and nearly one thousand wounded and a retreat across the Tugela River into British territory.

There are nearly three hundred Boer casualties.

British troops are defeated by the Boers at Ladysmith on February 8.

By taking command in person in Natal, Buller had allowed the overall direction of the war to drift.

Because of concerns about his performance and negative reports from the field, he is replaced as Commander in Chief by Field Marshal Lord Roberts.

Roberts quickly assembles an entirely new team for headquarters staff and he has chosen military men from far and wide: Lord Kitchener (Chief of Staff) from the Sudan; Frederick Russell Burnham (Chief of Scouts), the American scout, from the Klondike; George Henderson from the Staff College; and Neville Bowles Chamberlain from Afghanistan.

Like Buller, Roberts had first intended to attack directly along the Cape Town–Pretoria railway but, again like Buller, had been forced to relieve the beleaguered garrisons. 

Leaving Buller in command in Natal, Roberts masses his main force near the Orange River and along the Western Railway behind Methuen's force at the Modder River, and prepares to make a wide outflanking move to relieve Kimberley.

Except in Natal, the war has stagnated. 

Other than a single attempt to storm Ladysmith, the Boers have made no attempt to capture the besieged towns.

In the Cape Midlands, the Boers had not exploited the British defeat at Stormberg, and have been prevented from capturing the railway junction at Colesberg.

In the dry summer, the grazing on the veld becomes parched, weakening the Boers' horses and draft oxen, and many Boer families join their menfolk in the siege lines and laagers (encampments), fatally encumbering Cronjé's army.

Roberts launches his main attack on February 10, 1900, and although hampered by a long supply route, manages to outflank the Boers defending Magersfontein. 

A cavalry division under Major General John French launches a major attack to relieve Kimberley on14 February 14.

Although encountering severe fire, a massed cavalry charge splits the Boer defenses on February 15, opening the way for French to enter Kimberley in the evening, ending its one hundred and twenty-four days' siege.

Meanwhile, Roberts pursues Piet Cronjé's seven thousand-strong force, which has abandoned Magersfontein to head for Bloemfontein.

General French's cavalry is ordered to assist in the pursuit by embarking on an epic fifty kilometer (thirty-one mile) drive towards Paardeberg where Cronjé is attempting to cross the Modder River.