This ‘FuSE: Fundamental Sciences E-infrastructure’ proposal brings together Nikhef, the Dutch institute for subatomic physics and ASTRON, the Netherlands Institute for Radio-Astronomy, with SURF, the national e-Infrastructure provider, to build and operate a nationwide e-Infrastructure. This e-Infrastructure will serve the most data-intensive and demanding Research Infrastructures on the National Roadmap: the LHC experiments ATLAS, LHCb, and ALICE at CERN (high-energy physics), the Square Kilometre Array (SKA, radio astronomy) and KM3NeT (neutrino astrophysics) and will thereby strengthen the already unique position of The Netherlands in providing joint e-Infrastructure facilities. In the 2020’s era of Exabyte data rates, the development of this e-Infrastructure will ensure that the national computing facilities are available and affordable. Without the work of this proposal, the Dutch computing costs and demands would be much higher, or conversely, this front-line computing and research capability would be unavailable to the community. Nikhef and ASTRON each fulfil national leadership and coordination roles in these global scientific facilities. These roles are the natural consequence of the Netherlands’ strategic investment in these facilities, and as a result, these are part of the Dutch National Roadmap. The science cases for the facilities are at the heart of the strategic scientific agendas of both institutes. Towards the end of the five-year term (2021-2025) of this proposal, all three infrastructures will be acquiring data at the Exabyte scale. Large-scale computing infrastructures are needed to ensure Dutch researchers have access to the resources necessary to properly exploit the nation’s major investments in these global endeavours. The similarities between the computing infrastructure requirements coupled with the cost-benefit of collaboration have led to this proposal. Embedding the proposed joint data-processing facility in the Dutch National e-Infrastructure (DNI) is expected The science cases of the three global research infrastructures drive the content and extent of this proposal. The LHC science cases follow from the LHC Upgrade proposal (2013) which funded construction of new detectors as well as computing for the period 2014 – 2019. The upgraded detectors will be installed in the coming two years and the LHC will start running again in 2021. The proposed facility is necessary to analyse these data and extract the scientific results. For KM3NeT the science cases are equally compelling: it is the only place in Europe where neutrino oscillations and cosmic neutrinos can be studied. The science cases of interest to the Dutch community for the SKA are among the highest-priority science projects identified for this global telescope. Whilst it will take until 2026-2027 for the full science capability of SKA to ramp up to full capacity we will be building on leading Dutch expertise in LOFAR, a critical SKA pathfinder telescope, to blaze the way to significant leadership and impact from the new SKA. Given the investments that the Netherlands has made over the past 10-15 years, it is a matter of national pride that the two highest rated key science projects for SKA are the study of the Epoch of Reionisation (mapping the evolution of the first stars and galaxies) and timing pulsars to test extreme physics (of matter and gravity). Furthermore, we aim to deliver an e-Infrastructure that will be ready for the emerging field of multimessenger physics, exploiting data from a number of detectors and telescopes to enable fundamental discoveries. In the longer term, this will include yet another infrastructure on the National Roadmap: the 3rd generation gravitational waves detector, Einstein Telescope. The proposal covers the period 2021 - 2025. The total budget is M€ 28,8. Of this amount M€ 10,5 will be provided by the DNI (SURF), as the continued support of the Dutch LHC (WLCG) Tier-1. ASTRON and Nikhef will together co-fund M€ 6,4. The Roadmap request is M€ 11,9. This proposal combines the interests of three Research Infrastructures and strives towards an even stronger position for the Netherlands in these experiments in full alignment with the Dutch national e-Infrastructure.