use strict;

my @files = <DATA>;
chomp for (@files);

my @sorted = map {$_->[4]}
    sort { $a->[2] <=> $b->[2] 
           || $a->[3] <=> $b->[3] 
           || $a->[0] cmp $b->[0]  }
    map {[/(\d+)([A-Za-z]+)([0-9]+)/,
         { Jan => 1, Feb => 2, Mar => 3, Apr => 4,
           May => 5, Jun => 6, Jul => 7, Aug => 8,
           Sep => 9, Oct => 10, Nov => 11, Dec => 12,
         }->{$2}, $_]} @files;

print $_, "\n", for @sorted;

__DATA__
fwlog.14Jan2005.gz
fwlog.14Dec2005.gz
fwlog.14Dec2004.gz
fwlog.14Dec1901.gz
fwlog.14Mar2005.gz
fwlog.15Mar2005.gz
fwlog.16Mar2005.gz
fwlog.17Mar2005.gz
fwlog.18Mar2005.gz
fwlog.19Mar2005.gz
fwlog.1Mar2005.gz
fwlog.20Mar2005.gz
fwlog.21Mar2005.gz
fwlog.2Mar2005.gz
fwlog.3Mar2005.gz
fwlog.4Mar2005.gz
fwlog.5Mar2005.gz
fwlog.6Mar2005.gz
fwlog.7Mar2005.gz
fwlog.8Mar2005.gz
fwlog.9Mar2005.gz