The Imperial War Museum has secured £4.5 million from the Heritage Lottery Fund to help finance the creation of new galleries which are due to open in time for the centenary of the outbreak of the First World War in Summer 2014.
The Heritage Lottery Fund gave its initial support to the project last November and at the end of July confirmed a grant of £4.5 million.
HLF's latest grant comes on top of the £15.3 million the museum has already raised towards the the total £35 million cost of its First World War centenary redevelopment project.
The remaining £15.2 million is being sought from a variety of sources including donations from philanthropists, trusts and foundations, corporate partners, IWM friends and the public.
The wind-down of the museum's current exhibitions begins in September.
"We're delighted to announce that we have secured this grant from Heritage Lottery Fund," said Diane Lees, director-general of IWM.
"Claiming the lives of over 16 million people and affecting even more, the First World War was a turning point in world history.
"The centenary is a landmark anniversary for Britain and the world and also marks the opening chapter of IWM's history.
"IWM was originally established in 1917 to collect and record everybody's experiences of the Great War, which was still being fought.
"A hundred years through our new galleries at IWM London and wider centenary programme, IWM will reconnect people with the First World War and keep the history and personal recollections of the war alive for future generations."