raid - mdadm, RAID5 all disks marked as spare, won't start

RAID5 config with mdadm and 4 disks

After some incidents, eg one of the drives was lost, had to reboot the server and rebuild the array, my raid is in a funny situation

cat /proc/mdstat

Personalities : 
md0 : inactive sdb[1](S) sda[4](S) sdd[3](S) sdc[2](S)
      7814057984 blocks

unused devices: 

mdadm -E /dev/sd[a-e] | grep Event

     Events : 946860
     Events : 946860
     Events : 946848
     Events : 946860

mdadm -D /dev/md0

mdadm: md device /dev/md0 does not appear to be active.

mdadm --assemble /dev/md0 /dev/sda /dev/sdb /dev/sdc /dev/sdd --force --verbose

mdadm: looking for devices for /dev/md0
mdadm: /dev/sda is identified as a member of /dev/md0, slot 4.
mdadm: /dev/sdb is identified as a member of /dev/md0, slot 1.
mdadm: /dev/sdc is identified as a member of /dev/md0, slot 2.
mdadm: /dev/sdd is identified as a member of /dev/md0, slot 3.

mdadm: ignoring /dev/sdb as it reports /dev/sda as failed
mdadm: ignoring /dev/sdc as it reports /dev/sda as failed
mdadm: ignoring /dev/sdd as it reports /dev/sda as failed
mdadm: no uptodate device for slot 0 of /dev/md0
mdadm: no uptodate device for slot 1 of /dev/md0
mdadm: no uptodate device for slot 2 of /dev/md0
mdadm: no uptodate device for slot 3 of /dev/md0
mdadm: added /dev/sda to /dev/md0 as 4
mdadm: /dev/md0 assembled from 0 drives and 1 spare - not enough to start the array.

I know that one of my drives, /dev/sdc is about to fail as I get SMART reports for bad sectors (7 bad sectors)