In this paper a 2-1/2-dimensional hybrid code is used to examine the collisionless large spatial scale (kc/&ohgr;pi~1) low-frequency (&ohgr;~&ohgr;c;) interaction initiated by a plasma shell of finite width traveling at high Alfven Mach number relative to a uniform background plasma. Particular attention is given to the angle of the relative velocity relative to the ambient magnetic field for the range of angles 0<&thgr;<&pgr;/2. An attempt is made to parametrize some of the important Physics including the Alfven ion cyclotron instability, the field-aligned electromagnetic ion counter streaming instability, mixing of the plasma shell with the background ions, and structuring of the interaction region. These results are applicable to various astrophysical interactions such as bow shocks and interplanetary shocks. ¿American Geophysical Union 1987