One year on from the 7 October Hamas attacks, tough questions are still being asked within Israel about the deadliest day in its history, when the country's powerful army was caught off guard and swiftly overwhelmed. The Nahal Oz base was overrun by Hamas gunmen on the morning of 7 October and more than 60 Israeli soldiers are reported to have been killed - with others taken hostage. Israel's military is yet to publish its official inquiry into what happened there that day, but it has already briefed relatives of those killed there, and some have shared those details with the BBC. In an attempt to further piece together events, we have also spoken to survivors, seen messages from those who died, and listened to voice recordings reporting the attack as it happened, helping to build a picture of the speed and ferocity of the invasion.