In the winter of 1979/80, five petroleum companies participated in an Exxon Production Research Company program in which thirteen large-scale ice strength tests were conducted offshore in the vicinity of Prudhoe Bay. The purpose of the program was to determine the uniaxial compressive strength of annual sea ice as a function of strain rate and direction of loading with respect to preferred crystal alignment. Full ice sheet thickness test blocks with dimensions of 10 ft × 20 ft (3.05 m × 6.10 m) were cut free from the surrounding sheet ice. A hydraulic loading system with two million pounds of force capacity was used to compress the ice blocks at constant strain rates ranging from 10−7 s−1 to 10−5 s−1. Deformation in three orthogonal dimensions along with the axial had were measured and recorded throughout the test. This paper describes the field operations and test results, including uniaxial compressive strength, stiffness, Poisson’s ratio, and failure modes. Measured ice temperature, salinity and crystallographic structure are also presented.